Nix / NixOS

oh my goodness, I feel so heard right now, that's exactly as I always felt, I'm glad I'm not the only human obsessing over these things (well, not meaning that I enjoy your struggle lol).

I also don’t want to be too personally identifiable

I think you could do like some other accounts I've seen doing, merging their name and surname in some peculiar way, I did the same, but just for having a sort of unique, easy to use handle, I still keep my actual git username as my real one because I want to be identified with it. You on the other hand could do that and also use the same nickname as the git username. Another system I've always liked is to use this neat page on Perchance that generates an adjective-animal couple and they are so convenient for making up random names.
If you go all out and keep one identity and in the clear too, big respect, I don't do it because I never want to end up in a moment where I wonder "what I'm going to do is a bit in a gray area of acceptable, should I make a new account for this?" as that's going to break all the continuity that is useful to stay connected with the community. When sioling the two identities, I can do everything with much more peace of mind.

I laughed at “adult friendly” but that’s seriously apt.

Very happy that the humor came across 😆
And seeing how exotic/esoteric nix looks to older people, yes apt is way more adult friendly than nix