In the spirit of the AU, I'm going to nix the "literally raised by birds in the woods for years" angle, but she's welcome to have gotten lost in the woods at some point while younger (maybe not for literal years) or to just generally believe that to be the case. Kids develop fantasies, and that's perfectly fine! But an actual feral child is a bit much, and I'm not super confident in my own ability to sensitivity read and deal with that from a mod/npc angle.

Nonverbal with a communication app or something like that is fine, nonbinary using a male PB is also fine.

As for adding staff in general, I'm going to say that it's fine but should be done sparingly if possible, just for the characters that are critical to transferring your character into the setting. For example, if someone apped a Pokemon protag, if they have a plot-relevant parent, that parent could be put on staff, but just tossing gym leaders in to fill staff wouldn't be ideal, since we want everyone to have as much opportunity to fill their characters into the setting as possible.