I love trans Neil headcanons for a number of reasons, specifically how funny it would make how everyone reacts to him having a secret identity is
His father being like “I don’t care that my child is trans, I will respect his pronouns, I’m just going to kill him for unrelated reasons”. Also the idea of him finding out Neil is trans and being like “Oh ok. Your new name is Nathaniel, after me, obviously. Anyway, when you’re dismantling a body your instinct will be to go for the joints, however-“
Riko, and by extension Kevin and Jean, just seamlessly accepting Neil’s new gender into their fucked up codependent evil situationship without missing a beat because Neil’s gender doesn’t matter so long as he’s good at Exy. The others being like “Wait you knew Neil used to be a girl and didn’t mention it?” And Kevin just being like “What does it matter, Exy is a unisex sport, he would be allowed to play either way” and that’s just as far as his brain got
Andrew hooking up with Neil and getting his hands in Neil’s pants and internally going “Well that’s unexpected but honestly still probably only the third most unexpected thing about him” and then just carrying on
And most of all that it would be in character for Neil to not mention it as a narrator because if it doesn’t pertain to Exy, the mafia, or Andrew and Kevin then he’s probably just not even going to consider it relevant