I have a clear demarcation:
PC : Heavy duty games (heavy in terms of required system power, graphics, physics, FPS combat, etc)
Steam Deck: Light games which can run on a potato (and hence run well on the Deck)
Which ends up meaning i play all my small/indie/cosy games on the Steam Deck, which is perfect for me. If i want to play a big, graphically intensive, AAA title, then i use my powerful PC and large monitor to get the best experience out of it.