Earlier quoted context omitted.
I got a steam deck - it makes a very decent attempt at transforming the former experience into the latter, but keeping access to all your existing PC games.
How well does it succeed? One reason I've only played games on consoles is that if I see a game that has PS5 on the box, I know it will run on my console. Do Steam games make a similar promise for the Steam Deck?
Assuming the game itself runs fine, usually the main issue is mapping steam deck controls to the in-game keyboard and mouse config. I find the UX for doing this to be pretty confusing and terrible (doubly so when using an external controller), but this is helped some by the fact that you can apply controller mappings submitted by other Steam users.