Great suggestions in the comments, especially in regards to great sub-10 dollar indies and the use of Isthereanydeal, but I’d also like to throw in a recommendation to not forget about Desktop mode.

If your budget is tight, the deck basically offers a portable PC, including emulated games up to GameCube era and other free non-steam things. Things like emudeck and heroic game launcher can also add shortcuts to steam mode, although I didn’t really use the latter since I didn’t use Epic or GoG.