As it turns out, it doesn't take that much effort to make packages that comply with Fedora/openSUSE Packaging Guidelines and Debian Policy with this tool, and it has drastically simplified my ability to maintain software across distributions in a way that still cleanly integrates with the distribution platform.
This is how the Spacewalk Debian/Ubuntu client packages are built[3][4], among many other things. There's also a few other examples out in the wild[5][6][7].
At least for the stuff I make for myself, I haven't made packages that fully pass lintian, but it's not terribly difficult to do if you want to.
[1]: https://github.com/ascherer/debbuild
[2]: https://openbuildservice.org/
[3]: https://gitlab.com/datto/engineering/spacewalk-debian-client...
[4]: https://build.opensuse.org/project/show/systemsmanagement:sp...
[5]: https://pagure.io/python36-flatpkg-deb
[6]: https://pagure.io/rpmdevtools-deb
[7]: https://build.opensuse.org/package/view_file/Virtualization:...
https://github.com/kakwa/amkecpak
It doesn't exactly simplify the Debian packaging in my case as it leaves the packaging mostly exposed.
But it provides a lot of far more convenient and easy to remember commands (make rpm, make deb, make deb_repo, make rpm_repo, etc) compared to the easy to forget options of rpmbuild/mock and dpkg-buildpackage/cowbuilder.
It also glues everything together from upstream source recovery to building the final repository ready to be rsynced on a public server.
It won't pass all lintian tests due to the ridiculous requirements and useless ceremony "correct" Debian packages need. Still working on it.