Nonbinary Spanish

So I've been researching nonbinary Spanish pronouns and other words, and checked them with a couple Spanish speakers and a linguist, and now I shall attempt to explain them. For an overview of the gendered basis of Spanish grammar and how it works, please see my previous post.

Disclaimer! I spend most of this post talking about this topic like there are end-all be-all answers, like I am giving a lesson on well-established rules of parts of speech. I am not. Most of these were invented by someone else, but like in English, there will probably be other people using the same words in new ways and making up their own words. I am merely trying to explain, as clearly as possible for as wide an audience as possible, what I think I have been reading are things people are doing. Thank you.

Mostly, it seems, gender-neutral words are being created because of feminist leanings in Hispanic culture that object to the way mixed groups are always referred to as male plural. A group of boys is 'ellos'. A group of girls is 'ellas'. A group of 20 girls and 1 boy is 'ellos.' Also, there are certain job titles that change with gender: el profesor/la profesora. But there are certain that don't, or that are otherwise problematic. El secretario carries the same connotation of 'secretary' that 'secretary of state' has. La secretaria carries the connotation of the office job that involves answering the phone does.
I think it would make sense to define the parts of speech I'm going to be talking about.

Definite articles:
These talk about things that you know exist. "The woman who understands computers" vs "A woman who understands computers" might be a good example of the difference between definite and indefinite articles. The first refers to a specific person, and the second does not.
The definite article in English is 'the'. In Spanish common usage, there are four: the masculine (el) and feminine (la) in both singular and plural. In Spanish, the definite article is, almost without exception, how one tells the gender of the noun. It's only useful (for trans people, anyway) to create a gender-neutral definite article in certain situations, and here's why. Words like 'person' and 'human' are already gendered, and don't change gender based on who you're talking about. La persona is always la persona, even if you're referring to a guy. Those job titles that do change gender provide the most obvious use for gender-neutral definite articles. Gender-neutral definite articles include le (les) and ol (oles), the second of which implies agender. To summarize:
        The male student = El estudiante
        The male students = Los estudiantes
        The female student = La estudiante
        The female students = Las estudiantes
        The gender-neutral or unknown gender student = Le estudiante
        The gender-neutral or unknown gender students = Les estudiantes
        The agender student = Ol estudiante
        The agender students = Oles estudiantes
 I haven't seen it written, but I see no reason, if it strikes your fancy, you couldn't use 'Li estudiante' and 'Lis estudiantes' in place of 'Le' and 'Les'.
(Estudiante is a handy word that changes gender based on which student, but does not change ending. We'll get to endings later.)

Indefinite articles:
These talk about things you don't know exist. Indefinite articles in English include 'a' and 'an'. Plurals are less common, but an argument could be made for 'some', in the sense of 'What if some students were to try it?' Frequently we just leave it off. In Spanish, it's uno/una, with plurals unos/unas. I have actually not found anything on the internet regarding indefinite articles, but 'une/unes' seems logical and follows the patterns.
         A male student = Un estudiante
         A female student = Una estudiante
         Some male students = Unos estudiantes
         Some female students = Unas estudiantes
         A gender-neutral or unknown gender student = Une estudiante
         Some gender-neutral or unknown gender students = Unes estudiantes.

Personal pronouns:
You're probably most familiar with personal pronouns. As in English, 'I' and 'you' don't have gender, but the third person pronouns (he/she) does. Unlike English, third person plural (they) also has gender, depending on who's in it, as explained above. It's pretty easy to conjugate, though.
        He wants ice cream = Él quiere helado
        They, a group of men OR of men and women, want ice cream = Ellos quieren helado
        She wants ice cream = Ella quiere helado
        They, a group of women, want ice cream = Ellas quieren helado

Suggested new personal pronouns: Ele/Elles or Elle/Elles and Ol/Olles (agender).
        Ze, a gender-neutral or unknown gender person, wants ice cream = Ele quiere helado OR Elle quiere helado
        They, a group of gender-neutral or unknown gender people, want ice cream = Elles quieren helado
        Ze, an agender person, wants ice cream = Ol quiere helado
        They, a group of agender people, want ice cream = Olles quieren helado

Ello is technically a gender-neutral word, but it's quite archaic and tends to be used for concepts.


Direct and indirect object pronouns:
You'll probably remember hearing from school that the direct object receives the action. 'The child throws the ball.' Throws is the verb, and ball receives the action. You know you've got a direct object because there don't need to be extra words between 'throws' and 'the ball'. 'The child throws the ball to the teacher' has two objects, but you know 'teacher' is the indirect, not the direct, because you need the 'to' in there. The child does not throw the teacher. The teacher only comes into the sentence because the ball does.
Pronouns always replace nouns. The direct and indirect object pronouns in English are the same: it, him, her, or them. The child throws the ball = The child throws it. The child throws the ball to the (male) teacher = The child throws it to him. If your child were to nonsensically throw the teacher to the ball, the nouns' pronouns don't change: The child throws him to it.
Spanish is different. Direct object pronouns have gender: lo, los, la, and las. Indirect object pronouns don't: le and les. You use indirect pronouns a lot more in Spanish than you do in English--whether or not you mention who it's referring to. So if you have a direct object pronoun and an indirect object pronoun right next to each other, to avoid the awkward 'le lo' and 'le la', the 'le' changes to 'se'.
So let's say your child and teacher are male, and your ball by definition is always female.
        The child throws the ball to the teacher = El chico le tira la pelota al (a el) profesor
        The child throws the ball to him = El chico le tira la pelota
        The child throws it to the teacher = El chico se (le) la tira al profesor
        The child throws it to him = El chico se la tira.
If you have multiple teachers, your 'le' turns to 'les' but your 'se' stays. If you have multiple balls, your 'la' turns to 'las'. If instead of a ball, you're throwing a pencil, which is masculine, your 'la' turns to 'lo', and multiple pencils gets 'los'.
Obviously our indirect object pronouns are already gender neutral, but let's see what happens when we use 'le' and 'les' as gender-neutral direct object pronouns.
We'll keep our child and teacher male just for simplicity and start throwing a gender-neutral student. In English, I'll use the hir pronoun as the singular gender-neutral/agender counterpart of him/her, to differentiate between singular and plural, since plural is always 'them'.
        The child throws the student to the teacher = El chico le tira le estudiante al (a el) profesor
        The child throws the student to him = El chico le tira le estudiante
        The child throws hir to the teacher = El chico se (le) le tira al profesor
        The child throws hir to him = El chico se le tira.
In this case, multiple students becomes 'les'. Now, you're probably never going to need a construction this complicated. The only time you're likely to need a gender-neutral direct object pronoun is for a verb like hug. So:

        I hug the gender-neutral student = Yo abrazo le estudiante
        I hug hir = Yo le abrazo
        I hug the gender-neutral students = Yo abrazo les estudiantes
        I hug them = Yo les abrazo

Using the 'ol'/'oles'  direct object construction for agender is slightly les confusing, but just to be thorough:
        I hug the agender student = Yo abrazo ol estudiante
        I hug hir = Yo ol abrazo
        I hug the agender students = Yo abrazo oles estudiantes
        I hug them = Yo oles abrazo

For non-Spanish speakers, it's worth noting that there is a pronounciation difference between 'oles' and 'olles'. Double L in Spanish is pronounced like a Y, or in certain countries something like a J.
One site argues that the direct object pronoun 'lo', because it can be used to refer to an idea or to an unknown object, is gender-neutral, so one could arguably use that, but it follows the same logic that had English speakers for years using 'he' for an unknown person, and this is currently an unpopular idea.

Possessive pronouns:
These are gendered in English (her book, his book) but not in Spanish (su libro) so don't worry about them!


Noun/adjective endings
As I've said before, most nouns don't change gender. Some, though, do, and all adjectives do (though some adjectives, like verde, don't change spelling). I'll use 'the funny professor' as the example. You'll notice that some endings don't work very well with some words.
For context: 

        The funny male professor = el profesor chistoso
        The funny male professors = los profesores chistosos
        The funny female professor =  la profesora chistosa
        The funny female professors =  las profesoras chistosas
Some endings are already used, especially in writing, to denote men-and-women. These, however, do not leave room for neither-men-nor-women, and they tend to be unpronounceable.

        -(o/a)/(os/as) (los/las profesores/as)
        -@/-@s (l@s profesor@s)
        -Ⓐ/Ⓐs, tends to be used in radical political writing; Ⓐ is the anarchist symbol (lⒶs profesorⒶs)
There's also some nitpicking about whether these 'letters' should be made smaller to fit in sentences.
        -æ, works better for words that change from e to a rather than o to a (læs profesoræs)
        -x, loses the binary problem but maintains unpronounceability (lx profesorx)

Others work better for spoken language.
        -e/es, implies third gender (le profesore chistose, les profesores chistoses)
        -i/is (le profesori chistosi, les profesoris chistosis)
        -u/us (le profesoru chistosu, les profesorus chistosus)
        no ending, implies agender but is difficult to pronounce (ol profeso (?) chistos)
Remember that the pronunciation of certain letters changes when the letters next to them change. Changing the spelling of a word to maintain the pronunciation across tenses is quite common.
         Chico/chica cannot be chice or chici, but would change to chique and chiqui, as would any word with a C right before the o/a ending gaining an e or i ending. The u ending would remain the same.
         Largo/larga, similarly, would go to largue or largui, as would other ga/go endings receiving an e or i.


Citations!
Almost all the specifics came from nonbinary.org. I encourage you to explore it.
Discussion of certain word endings, use of elle, reasons for gender neutrality
On object and possessive pronouns, other languages, includes lots of new English pronouns
Discussion on the use of ello

If you have any corrections for me, or other sites with more updated material, please don't hesitate to send them my way!