Interesting. I thought I saw somewhere that Apple stopped applying macOS for some certification, but it looks like the latest versions of macOS definitely have UNIX certification.
Maybe what I saw was about POSIX certification, but it's shockingly hard to find definitive info on that online. I can find the list of UNIX-certified operating systems, but not the list of POSIX-certified operating systems, at least not from an authoritative source. The latest version of macOS is POSIX-certified but I can't tell if there were any gaps between 10.5 and now.
Everything since 10.5 Leopard (2007)
https://www.opengroup.org/openbrand/register/