In an unusual turn of events, I actually should have been a tiny bit more ambiguous in my original response :). We haven't decided what to do with RHEL9's source code yet. It may end up at
git.centos.org exactly as 8 does today. We're just not that far along in 9 development and those conversations haven't been finalized. I can say though - were I to put myself in a RHEL-9 rebuilders shoes though, best case source is exactly as its are today. Worst case I would have to look through the gitlab repo for specific versions I want as you've described above.