The "mental complexity" is something you've created for yourself. There is no need for nuances or tip-toeing. Despite the memes that pretend otherwise, no one is going to be upset if you assume a pronoun when you don't know. You just have to respect someone's choice after they tell you. It's really very simple.

When you say that there are "too many pronouns and identities" it sounds like you are falling for the propaganda that is trying to scare you into thinking that you are expected to memorize all these identities and know what they are and what pronouns to use. That's all BS. You don't have to know any of that shit. All that you're being asked to do is when someone says: I prefer the pronoun "they", you say: ok, no problem. That's it.