Emulators and some not totally legal, online required or denuvo, single player games (looking at you Rockstar)

How does that work exactly? I mean, I have deactivated my wifi and I logged off of my account and after a reboot, I just can go into my account in offline mode. I will eventually use my steam deck off wifi for sure and I want to know what could eventually happen. Thinking about dual booting Batocera and ditching Emudeck so I can still play my retro games if I get locked out of SteamOS.