Get your own ukulele, learn to play and inspire her to learn and get better! Ukuleles are great for jamming, so your second ukulele won't be a waste.

Learning to sing and strum chords at the same time was a transformative experience for me and incredible bang-for-buck compared to learning piano, because that immediately unlocks being able to perform most pop songs with chords. Someone above posted a great collection of pop songs written for ukulele that I can't wait to try playing tomorrow: https://sanjoseukeclub.org/song_book.html