Make Fedora Kinoite beta and nightly official testing Distros. It makes so much more sense to base off modern but tested packages, and to use an atomic distro for keeping the other issues aside.
But if you also need to support messy package based distros with their broken package managers, that is for sure problematic.
I used Elisa and found it quite unusable for folder-structured music.
I only used folder structures as I found no say so sync .m3u playlists including the music files between Android and Linux. Finding a way here would be great.
Merkuro looks so good! The previous calendar was unusable for me, but good KDE Software is really nice.
I wish the Akonadi stuff could run as a Flatpak runtime though, to support multiplatform. But I am not sure if this requires IPC or also native messaging.