Wikipedia shows Unix was first developed at the Bell Labs and later licensed to a few companies before its rights are finally sold to another company. What happened exactly with these licensing and purchasing? Today, which companies can legally produce and sell (genuine) Unix products?
From the Wikipedia article you linked:
[...] the UNIX trademark passed to the industry standards consortium The Open Group, which allows the use of the mark for certified operating systems compliant with the Single UNIX Specification (SUS).
Thus, if you go to the effort[*] of getting your OS certified, you can call it "genuine Unix". A list is available in the Wikipedia article on SUS (https://en.wikipedia.org/wiki/Single_UNIX_Specification):
AIX, EulerOS, HP-UX, Inspur K-UX, macOS, Solaris, and z/OS.
Even more OSes were previously certified but haven't been re-certified to the latest version of the standard.
[*] - I expect you'll also have to contribute a few grand to The Open Group to cover the costs of them verifying your implementation.