Lots of good suggestions already, but what first came to my mind is Final Fantasy Tactics Advance. I’m not even into Final Fantasy and have only played a few tactical RPGs, but I fell into FFTA hard when it came out. The battle system was fun, with a little twist that there’s random laws you have to follow each fight (e.g. no attacking with staves) that can get a character arrested and taken out of the action after a warning. Nice music, cute art style, and a pretty good story as I recall.

Save you a click: it’s GameStop.

Makes sense that it would match the inputs on the Steam Deck.