If she would get into it enough to practice, let her handle various semis from 9mm and up, and let her find the one she likes best, the one that she "fits" will be the one she enjoys, and will therefore be more interested in practicing with, setting up a happy positive feedback loop.
If she's not interested enough to practice much, stick with a wheelgun.
Duh! I missed that. I'm not all that familiar with that caliber to start with, so we'll have to try one out.