Steam Deck

Yeah, and shared progression is a decent reason for them to have anticheat as well.

For the mod side of things, Deep Rock Galactic has a pretty good approach. They have 3-categories of mods, verified, approved, and sandbox. Verified is client only (usually cosmetic) and is allowed in all games, approved mods require all players to have the mod installed but otherwise can be used in any game. However sandboxed mods are considered too disruptive to the game experience and require a separate save file. Players can create a "sandbox" copy of their save file at any time, so it's extremely easy to play around with the extreme mods without losing any of your base game progression.

While this approach to mods is great though, it's important to note that DRG doesn't really have anti-cheat to keep people from bypassing the mod system and cheating in public games. But hopefully by providing easy ways for people to "properly" have that experience, they can avoid most cheaters (similar to the idea that the best way to fight piracy is through good convenient options to be a legal customer). It works pretty well, but I do imagine it won't work as well in a game with a more PVP focus.