I have reviewed:

And most especially:

In an attempt to build RHEL8 sssd RPMs from  

In the past, I have attempted to build RHEL8 RPMs on RHEL8.  That is a fool's errand!  I realize that now, because RHEL is not self-hosting.

(I have loads of test RHEL & OL 7 & 8 servers available, no Fedora.)

So I have to stand up a Fedora server to build the RHEL 8 RPMs.  Currently, Fedora is at Fedora 35 and RHEL8 is based on Fed 28.  Is that ok, or do I have to find Fed 28?

I've reviewed the RHEL9 beta (which is based on Fed 35).  Doesn't seem that different than RHEL8.