bring games to friends house and play, thats how the ps4 won the 8th gen console wars, it was a selling point of the console.

setting in big picture to look for a physical media directory, similar to non-steam games. the directory would be something like "USB Drive (E:)" or "DVD Drive (H:)" then if the directory contains "steam.cfg" or something like that, read it and get the name, executable, launch arguments, library info, and key (to make sure it works like the family sharing feature and someone cant just sell a bunch of stolen games)

steam deck: basically the same, just automatically configured. uses sd cards like other handhelds that use cartridges.

1. storage space
2. quick access on a new computer
3. game sharing (again)
4. offline purchases, steam goes down sometimes
if the steam key hasnt been redeemed then it will automatically when connected to the internet
5. sell in game stores, more people see the games and notice its for steam deck, they now know what a steam deck is, they buy steam deck, steam deck sales go up, companies notice and capitalize, more games for linux, can actually game on linux, apps get ported because more market share, more linux use, ♥♥♥♥ windows.

consoles are more powerful than handhelds because they dont have to worry about a really small form factor and a battery.

probably better ways of going about it or things that could be executed better but this is just my idea.