Although I'm a cis woman, I have never felt especially pleased with being lumped into this category. I have never listed my pronouns before, ever, and I avoid listing my gender if possible, because I do not want the first thing people to know about me be my gender and then view me through that lens. I have always appreciated the trans community overlooks my femaleness and sees me instead. In real life daily, to my great displeasure I am lumped into one of two boxes; the internet is a welcome reprieve.
I am not nonbinary, I do not prefer they/them. I go by she/her, but I don't want to advertise this. I have my own struggles with gender, even if I'm ultimately cis, and forcing me to report my gender in my username seems frankly gender essentialist.
I did not choose my pronouns.
What should I write? (none) is wrong, because I can be referred to with pronouns.
(ally) might be nice, except in LGBTIA+, "Ally" implies being straight, and I'm not straight.
How about an empty ()? to indicate I acknowledge the system but opt out personally. Or something cute like (friend), or comrade (but I don't know all the implications of that)