Yep! I worked at CodeWeavers during Proton development and we were basically contracted by Valve to build the whole thing for them. Although if projects like that interest you, the work on supporting Wine on MacOS after they drop 32 bit application support is amazing!
The executable in /Applications is 32-bit, but it's just a launcher for the real Steam app in ~/Library/Application Support/Steam/Steam.AppBundle which is 64-bit.
Ahh thank you! I knew I was missing something... I'd get the alert message, then the Steam app would seemingly close and re-launch. I wonder why it is architected like that.
I guess that it's like that in order to be able to update the executable for non-privileged users (who can't write to /Applications), which could be e.g. kids' user accounts in the family computer.
