> What allows Wine to run so many Windows apps that there's not an equivalent for MacOS? Is it lack of interest? Is it a technical thing?
It is a technical thing.
The XNU[0] kernel, which underpins macOS and is detailed by the exceptional book "Mac OS X internals"[1], can theoretically run on many x86 and/or ARM machines. However, the issue with running macOS apps via other operating systems is not the OS, but instead are the GUI frameworks expected (i.e., Carbon[2], Quartz[3], etc.). These frameworks are intentionally written for Apple hardware/macOS distros. Which makes sense when viewing macOS as a selling point for selling Mac's.
0 - https://en.wikipedia.org/wiki/XNU
1 - https://openlibrary.org/books/OL17205558M/Mac_OS_X_internals
No? Windows also has its own graphics subsystem, compositor, and an even bigger set of user land UI/forms/controls libraries than Mac OS. It really is just a critical velocity / adoption / time thing, there’s nothing strongly technical separating Mac OS API/ABI translation from Windows ala wine.