If it is targeting UNIX then it must work on Mac. Echoing your words, UNIX has stringent requirements to be UNIX and macOS fulfilled those requirements.
MacOS IS UNIX.
As a side note for fun, Linux is not UNIX and that’s intentional. Freedom is nice. ;)
Linux is not UNIX™, but it is a Unix in most meaningful senses of that term. My opinion would be that making much of the distinction would be pedantic in a negative sense; there does not seem to be a practical reason for this.
MacOS IS UNIX.
As a side note for fun, Linux is not UNIX and that’s intentional. Freedom is nice. ;)