The Steam Deck can behave like a Switch; if you want to stick to just Steam games with a big ✅ verified icon then it will probably be a similar experience, just with a different library of games (and better sales).

The Steam Deck can also be a full PC; you can plug in keyboard, mouse, screens, whatever, and use it to replace your laptop/desktop if you really want.

The middle ground is that the Steam Deck can be an incredibly versatile gaming machine. I can play the verified Steam games, I can usually play the non-verified games, I can install Heroic/Lutris and install all my free Epic/GOG/Amazon games with minimal tinkering, I can install emulators and run all my old Nintendo games at better resolutions and frame rates, and if I really feel like tinkering then I can install whatever else I want and try to get it working, but I always have all the reliable games to fall back on if I can’t!