For quite some time, I've been building lightly modified PGDG packages, but I have never figured how PGDG's yum repo gets debuginfo packages. When I have built them, unless I hack up the spec file to have "%debug_package" I do not get such a debuginfo package. Clearly, that is not how the spec files work as-is in pgrpms.
How do you invoke rpmbuild?
I get debuginfo packages. I build srpms then rpmbuild --rebuild them. Usually using mock, though moving toward docker these days so I can use the same toolchain for my debian build pipeline too.