This is a quote from the developer, before Apple announced that future hardware will run on a different chip that essentially bifurcates future Apple computers.
I'll let you draw your own conclusions from that.
QuoteAbout half of the macs (in the steam hardware stats) have fairly low end GPUs. That's out of the approximately 3% of the user base that mac accounts for. So it's only about 1-2% of potential users that have a mac and have a mac with a GPU that will play the game well. Apple's not made development life any easier with their notarization and other issues. So at least for this demo and the near term future I'm not spending time on the Mac build.