I rebuilt the mac download from a newer 2019 version of Unity. I hope it works! I can't really test it from my bedroom here...
Seems like I need a mac running Catalina to pull some sort of post-build xcode magic and validation process. I just don't have the hardware or time for this...
https://gist.github.com/dpid/270bdb6c1011fe07211edf431b2d0fe4