It looks like a scratch-build completes successfully: https://koji.fedoraproject.org/koji/taskinfo?taskID=88626062. If you do not wish to maintain python-straight-plugin in epel9, or do not think you will be able to do this in a timely manner, I would be happy to be a co-maintainer of the package (FAS gotmax23); please add me through https://src.fedoraproject.org/rpms/python-straight-plugin/adduser