You can set whatever pronouns you want people to use for you, even if you don't use them irl, and if you don't care at all you can set [any] or [none/use name]. Totally not disrespectful to use different pronouns in different places, lots of people playing around with their gender do this.

One of my favorite usernames here has always been that of @GenderIsOpSec@hexbear.net, so i can relate.

In my opinion it's perfectly fine if you pick a gender neutral option for the sake of anonymity. You should just go with something you're comfortable with. I know people who've tried to adapt they / them as secondary pronouns to normalize that and quickly dropped the idea because it actually made them feel dysphoric. I went with they / them for a few months when i started questioning my gender because i needed something more open-ended before i was certain i'm a girl and could go with she / her, and i tried that out using the tag system on here because i was still in the closet back then. Ultimately, pronouns are about a very basic right - having autonomy over how people gender you. That means it's up to you and nobody else to decide which pronouns you go with, and given how gender identity works, that can mean there's options that just feel very, very off, alienating or even hurtful when they're actually used on you. It's perfectly ok to experiment a bit with pronoun options and see what fits both you and your opsec needs. Hexbear even has comrade / them pronoun tags. We also have pronoun options like none / use name, and i actually know a couple nonbinary people who prefer that over pronouns IRL, particularly because neopronouns are even less common in my 1st language than in English (although they / them or our localized variant dey / dem / deren is by now established in queer communities here in Germany).

We aren't the pronoun police. Use whatever is convenient for you and we respect it.