or would that generally be regarded as, well, something akin to cultural appropriation? or as malicious adoption, like “i identify as an attack helicopter”?
It’s none of those things.
It’s more akin to pretending your name is Matt even though your name is Tom. You’re not going to offend anyone, and if it turns out that Matt feels right for you, then go for it, you’re Matt now. But if you’re not Matt, and don’t feel like Matt, then calling yourself Matt won’t achieve much for you or anyone else.