Not sure why people here are all arguing about why you would want to use discs, rather than the fact that the Steam Deck is a PC, of course you can absolutely used discs. All you need to do is plug in a USB disc drive, and it’s ready to go.
I’ve installed a bunch of my older PC games from CD/DVD that way, and it works great. Even under Linux, applications like Lutris make installing Windows game discs pretty easy, and once they’re installed, you’re ready to go.
Not sure why people here are all arguing about why you would want to use discs, rather than the fact that the Steam Deck is a PC, of course you can absolutely used discs. All you need to do is plug in a USB disc drive, and it’s ready to go. I’ve installed a bunch of my older PC games from CD/DVD that way, and it works great. Even under Linux, applications like Lutris make installing Windows game discs pretty easy, and once they’re installed, you’re ready to go.