

I have not tested them on the Deck, but the We Were Here series of games is great two-player puzzle-solving fun. At least the latest titles are Deck-verified, not sure about the older ones. You can play them in any order you wish - although I’d leave Forever as the last one to be played.
It Takes Two is another brilliant two-player adventure puzzle game. Only one person needs to buy it, the other can download the friend pass to play (although you cannot get achievements without buying the game).
I’m all for competition and against forced DRM. But the PC gaming service ʀᴇᴅᴀᴄᴛᴇᴅ that you’re referring to offers genuinely good services on top of just accessing games - social platform, (voice) chat, remote play (together), streaming video to friends, communities, easy access to mods, linux support, makes multiplayer easy, etc…