It does not matter if the package installs .py, .so or different files. Packages that simply drop a .pth file to site-packages or even only carry dist-info folder still need to Require the package that owns /usr/lib(64)/pythonX.Y.
See https://lists.fedoraproject.org/archives/list/packaging@lists.fedoraproject.org/thread/UFKUM5UKCTNGIT3KJVYEI5VXPI23QMBN/ Flatpak builds redefine %_prefix and the dependencies should remain present. Also get rid of one useless ^ and prep the pattern for two digit Python major versions. Add a test that tests that we match our default %_prefix (was the case even before this commit).