Comment by philo23

I believe that was part of the original plan for Proton, but with the success of the Steam Deck that got shelved and it moved to a focus purely on Linux.

I don't think it's ever likely to return any time soon, but it'd be cool if it did. Valve seemingly have very little interest in macOS at the moment.

CodeWeavers work closely with Valve and the Wine project to improve compatibility with games, and Apple's own Game Porting Toolkit is based on CodeWeavers work on Wine too. So all the pieces are there in theory.