Providing _a posix filesystem_ as a kernel abstraction is what I said. Which is not very standard for microkernels, and makes it (redox) pretty unix like at the kernel level.
The overall point being that both, microkernels can be unix likes, and redox particularly and at the kernel level leans in to being a unix like.
> So if Microsoft bothers to certify WSL2 then Windows is now UNIX?!?
Of course, the WSL2 layer would be UNIX. There is more than it so calling Windows exclusively unix would be wrong (in the same way that running Windows under a VM, or Winde, on an unix system doesn't make it Windows.