Who holds the canonical unix repo?
Unix (1969) predates source version control (1972).
https://www.opengroup.org/about-us/who-we-are
https://www.opengroup.org/trademarks
Together with IEEE they are the ones giving the POSIX certification http://get.posixcertified.ieee.org/certification_guide.html
I think the copyright of the old Unix code ended up with Novell in the 90s, so it would now be owned by Micro Focus.