Several Debian folks are working on a way to make it easier to use external repositories on Debian. They're collecting a list of external repositories, and it'd be nice (speaking as a user) to have upmpdcli there.
https://salsa.debian.org/extrepo-team/extrepo-data is where the data is being collected. It appears that the repositories you already maintain would qualify.
Just to be clear again, I'm just a Debian (and upmpdcli) user. I'm not a Debian Developer. I'm not involved in the extrepo project.