macOS (it’s not called OS X any more) is listed as XNU.
And of course it would list every BSD instance. Supporting them isn’t automatic when you’re taking about pre-compiles binaries because they can have subtly different ABIs. POSIX helps here but mostly at the source level, an ELF compiled for FreeBSD wouldn’t automatically run on OpenBSD nor NetBSD. The fact this does is unusual and deserves calling out.
