While it's not quite Verified for Steam Deck just yet, Moonlighter 2: The Endless Vault should be a reasonably good experience. It's rated Playable by Valve, with a note that some text is a bit too small. The developer has confirmed they plan to solve that as soon as possible too.
So what is it? From the Steam page: "Dive deep into Action-RPG with roguelike elements and a tale about new beginnings. With no coin to your name, you and the other townsfolk find yourselves stranded in the distant village of Tresna. Now, it’s up to you to get back on your feet and turn your humble shop into the beating heart of the village’s wealth. Explore dangerous dungeons, gather relics, sell them, and reinvest in your friends’ establishments. Unlock new weapons, armor, shop decorations, and—more importantly—restore hope that things can one day turn around."