Den sista “äkta” Unix-versionen finns där du minst anar det
But this illustrates the difficulty of defining precisely what the word “Unix” means in the 21st century. It hasn’t meant “based on AT&T code” since Novell bought Unix System Labs from AT&T in 1993, kept the code, and donated the trademark to the Open Group. Since that time, if it passes the Open Group’s testing (and you pay a fee to use the trademark), it’s UNIX™. Haiku hasn’t so it isn’t. Linux has so it is. But then so is z/OS, which is a direct descendant of OS/390, or IBM MVS as it was called when it was launched in 1974. In other words, an OS which isn’t actually based on, similar to, or even related to Unix.
Which means that the last officially trademarked commercial UNIX™ is Apple’s macOS 13, which underneath the proprietary GUI layer is mostly an open source OS called Darwin anyway. The kernel, XNU, is based on Mach with an in-kernel “Unix server” derived from FreeBSD.
Personligen tycker jag Unix är mer av en filosofi än ett stenhårt regelverk. Haiku, FreeBSD, Linux, macOS… de har i princip samma filstruktur och samma “tänk”, så i min värld är de alla Unix på ett eller annat sätt.