Reddit, where sanity goes to die. According to Reddit, it's perfectly fine to list a game like GTA V Enhanced as Playable on Steam Deck, even though online play is intentionally blocked, because single-player works.
https://www.reddit.com/r/SteamDeck/comments/1je36k4/comment/mif90p3/
Person 1: "Hey guys, check out GTA V Enhanced on Steam Deck. It's Playable!!"
Person 2 who just bought it: "Uh, but online doesn't work?"
Person 1: "But it's Playable offline!"
🙃