A popular insider is arguing that Sony won't allow PC ports on future Xbox consoles. Many gamers disagree since any Windows-based system should support Steam. Microsoft may soon release an Xbox handheld that could act as a test case for booting PlayStation's cross-platform games.
Between this and infinity nikki actively blocking non SteamDeck devices I have a feeling that Valve will bring the hammer down on this sometime soon.
When people buy a game, the store front says it should run and then it doesn’t they’re not going to yell at the developers. They’re going to yell at the store and I doubt Valve wants to bother with the extra support workload that entails.