Stardew Valley stays on the list. I have it installed, but haven’t played it much on my deck (other than to test mods). I have met other people with Decks who mostly play SDV, and it is a classic.
Monster Hunter: World, played that. Played it with my eldest who also has a Steam Deck. Runs pretty well, but there’s a lot of text for smaller screens (and aging eyes).
Now Vampire Survivors, that game is great for the Steam Deck. Short, defined games. The sleep mode has never failed, and if it did, you are only loosing a ½ hour run at most.