Please allow us using FDM on Fedora or other RPM-based Linux distros. I simply cannot install FDM on Fedora, because it expects RPM, not DEB.

YES!
i'm on openSUSE and I really want to install FDM but unfortunately it's not possible.

Hello,
Did not you try to use some converters from DEB to RPM?
For now, it seems we have no time for this. Maybe, just an .tar.xz can be a good enough replacement?
We can provide it along with the DEB version with no additional cost of the development