In an RPG I had a population glob beings. The species was called glob, all of the personal names were glob, and the pronouns were all glob. Henceforth, I shall use the pronouns glob/glob for you (if you don't mind).
I heard that all words were just made up, but the cutoff for new words ended a while ago. That's right, if you can't find a reference to a word in a book written no later than 19th century (in English, by a man, preferably aristocratic), we're taking that word away.
I'll respect your identity, and I can use a neopronoun if it is a standard one adopted by the community, but neutral pronouns should always be a valid option in any sentence too. I can't promise I'll remember a custom word you made up exclusively for yourself. I already have trouble remembering people's names.
If we're close friends, sure, I'll stick to whatever you like. But if I talked to you once in a 10 minute meeting last year, "them" it is.
I currently list my pronouns as she/xe/it/thon/ꙮ, with the idea being that people will have a range of options regarding which word to use: if they like, they can choose to just stick with one pronoun, probably she or it, and forget the rest; and if people do choose to refer to me using a neopronoun, then they can more or less use the spellings or pronunciations or inflections or agreements that work best for them. And this seems to be how most neopronoun users are: virtually all neopronoun users also go by an auxiliary pronoun (he, she, they, and/or it) for accessibility's sake, and virtually all neopronoun users are also very forgiving about how their neopronouns are used.
For me it goes a step further, since I'm good with being called pretty much any neopronoun, even though xe/thon/ꙮ are my favorites; and I'm even OK with being called he or they in a few specific contexts. I don't really bother explaining all that, though, since nobody wants to hear a treatise about autistic non-binary transfemininity in the middle of a pronoun circle, so that's why I usually just list my five favorite pronouns and call it a day.
So all in all, while we all have our linguistic preferences or sometimes complicated feelings regarding how we're referred to, the main thing that matters is that people just try to use our pronouns at all. So the problem with neopronouns, in my experience, is that most people end up either dismissing "made-up words" out of hand, or they get so hung up on using the neopronouns "correctly" that they end up just not using the neopronouns at all. So either way, it all comes back to people's discomfort with using non-prestigious, non-standard language, and this discomfort is sort of justified by the stereotype that people have about neopronoun users being 100% self-centered and unaccommodating.
I think part of the problem is that most neopronoun users don't really think or know much about the linguistics (especially the pragmatics) of neopronouns, and this causes neopronoun users to be worse advocates for neopronoun usage... But I also don't think that people need to have a scientific knowledge of which words they prefer to be called, in order to have their preferences respected.
That's the thing: you can use basically whichever pronunciation or grammar you want. Since it's already non-standard language, prescribing how to use it is beyond pointless. But if you absolutely need prescriptions, then my own tendency is to use the paradigm ꙮ/ꙮm/ꙮr/ꙮrs/ꙮself with singular agreement, and the readings I use are seraph/seraphim/seraphir/seraphirs/seraphimself, sometimes indicated with ruby characters. But again, you're under no obligation to use even remotely the same inflections or readings — that's part of the fun.
As for the background:
The character is the Cyrillic multiocular O, which appeared exactly once in exactly one 15th century Old Church Slavonic manuscript to write the phrase "many-eyed seraphim". That is, ⟨ꙮ⟩ was originally a fanciful variant of the Cyrillic O, meant to look like a bunch of creepy eyes. After the letter was encoded into Unicode, it became a somewhat popular symbol online, often used for a sort of comedic horror effect, for instance by writing "ꙮwꙮ" instead of "OwO". This would've been at the peak of the whole "biblically accurate angel" craze.
It was from this horror-comedic usage of ⟨ꙮ⟩ that my closeted self first started replacing my deadname with ⟨ꙮ⟩ in certain contexts, under the pretense that I was "just being silly" and that "these people don't really need to know my real name, do they?". Later on, I saw that a few other people were using ⟨ꙮ⟩ as a neopronoun, so I decided to start experimenting with using that character as a neopronoun, too. I think that an essentially unpronounceable image of a bunch of eyes really captures the whole "wrong planet" vibe, and these sorts of Unicode/emoji neopronouns in general are a really creative use of language, since they're basically a form of mixed-script writing.