EL8 packages are part of 2.1 (https://yum.theforeman.org/client/2.1/el8/).
I was more reacting to the fact the long list of supported distributions had no mention of a very relevant current one, EL8.
Interesting - which RPMS did you build exactly?
For subscription-manager (this is the important one for Katello) I have filed a request with the team that maintains it to deliver a build that works on SLES15. There is one in the suse build system, but last time I tried to install it didn’t work
We build this six RPMs:
after some checks and howto publish we will share the RPMs