I've said this for years...
But if Apple were to start selling macOS by itself that is the single Apple product I would buy. And I'd pay a good deal for it too.
Its for-real SUS compliant UNIX with an outstanding graphics and window management subsystem and decent driver support for less than the thousands of dollars that whatever the SCO remnants currently call themselves, HPE, Oracle and IBM are going to gouge you for their OS and the hardware that runs it (in IBM, HPE, and Oracle's cases anyway).
While I'd love to use macOS, I have absolutely no desire to use Apple's overpriced hardware. I value function far over form and on Mac computers the form has been super-ceding the function for quite some time, but I would switch from Free and FuryBSD as my main UNIXlike in a heartbeat if Apple sold macOS by itself. Unfortunately the whole idea makes sense and would work, so it'll never happen.