The difference between the SteamDeck and the PlayStation that makes the Steam Deck a “personal computer” is that you can run whatever software you want on a Steam Deck. SteamOS even comes with “desktop mode” which works much like you’d expect a desktop Linux OS to work. If you don’t like SteamOS, you can simply install a different OS.

You can plug a keyboard, mouse, and monitor into a Steam deck

In general the Steam Deck is not the kind of device that is going to run things at max settings. You are gonna play at 720p30FPS low settings but be happy you can play at all on a train or airplane. It’s really meant to be a competitor to the Nintendo Switch than a replacement for a gaming PC.

You can stream from your PC to your couch or bed if you are at home.