My S/O has a 9-year-old niece who has a Switch and likes it. My S/O wants to get her a Switch game for Christmas. Her family also does somewhat strict price caps for gifts, and this year the price cap is set at $30.
It's been a long time since either of us were 9 years old, so we don't really know what a 9 year old would like, games-wise. Here's what we do know: she likes puzzles and puzzle-style games. She already has Minecraft on the PC and doesn't care for it much. It doesn't have to be a physical game, we can put a gift card code in a Christmas card. And that's all we have to go off of.