It is possible but for things like a steam deck you just move on to the next store or piracy. It’s so open you get trapped by convenience not by encryption or premium features.
You’re thinking of now not the future. It’s a great device at the moment. But it’ll become out dated with time and it’ll be easy for the next steam deck to be shit or for shitty practices to come into play.
And using the example of piracy/other stores means every device is fine. Just hack the device/remove the shitty practices and you’re good to go whether it’s a steam deck, Windows, Etc.
Devices will be outdated anyways. But the steam deck you don’t have to hack. You just enable things with touch buttons.
Valve learned from other consoles they get hacked anyways, so they enabled you to do all the mods - while at the same time you won’t have to fiddle with pirated games for a fee. Personally I don’t think this strategy will change - and if they release a more closed steam decknin the future piracy is an option again. On another device then.