Hello!
With the help of Neal, I've put together a mock-centos-sig-configs project to hold mock configs for CentOS SIGs: https://pagure.io/centos-sig-hyperscale/mock-centos-sig-configs
This should make it easier to build packages against a given SIG for testing and development using mock. The project currently contains configs for the Hyperscale SIG, but other SIGs are obviously welcome -- just file an issue or (even better) send a PR on Pagure.
mock-centos-sig-configs is already packaged in Fedora, and should become available in EPEL in a week or so: https://src.fedoraproject.org/rpms/mock-centos-sig-configs
Cheers Davide