Recently, I've ended up interacting with Fedora packages that use several different
"higher order" or "layered" tools on top of fedpkg.
I created this page:
https://fedoraproject.org/wiki/Layered_build_scripts_for_package_maintainers
which attempts to enumerate the ones I know of. It's certainly non-exhaustive,
so if you maintain a tool that's not listed there, please add it!