For me, the ideal Deck games are ones that don't lose anything when scaling down to the small screen and APU.
I'll never understand people playing high visual fidelity games at 30fps on Low settings on Deck, if that person has a more powerful PC to play the game on.
Meanwhile, something like Civilization VI basically loses nothing when played on Deck.
Hades and Tunic both make sense to me as Deck game picks.