I was including Linux there, as it follows a standard UNIX architecture.
There is a big difference in having POSIX support and being a UNIX.
Windows, IBM i, IBM z/OS, Unysis MCA ClearPath, Green Hills INTEGRITY OS, Genode and many other OSes have POSIX support, yet their architectures have nothing to do with UNIX.
With all these years the amount of UB, memory corruption issues and security exploits only got bigger.
We need a major IoT meltdown to get rid of it, unfortunately it won't happen until the industry lets UNIX clones go.