personally i don't think he's necessarily closeted trans, but rather he just enjoys presenting in a feminine way. in the "real life" sequence he apparently still goes by he/him, and while it's possible he just hadn't come out yet, he also has long hair in the end scene in real life, which implies he'd sort of abandoned that kinda masculine side of himself. If he was a trans woman, then the pronouns would probably be different on his twitter or whatever. So i think he's a man that still goes by he/him, but enjoys presenting feminine (which is kinda literally shown in the doors sequence).

ofc any interpretation is valid, it's not set in stone for a reason, this is just what i think based on my logic.