Can't we still have traditional repositories though? I personally dislike snaps and flatpaks because they usually are shipped with libarries hard-baked in rather than using separately-updatable libraries in the OS, using them also often means app duplication on per-user level and at least Snap didn't support Guest sessions (because of non-standard home directory path) the last time I checked.
If you don't want to use something like snap/flatpak then all the distributions using your PPA repository have to provide the same libraries packaged the same way, and at that point what are they going to even gain from being different distributions in the first place? If someone wanted to make a fork of Ubuntu but all the packages and contents are exactly the same as mainline Ubuntu then they'd just use Ubuntu.
It evidently isn't working well enough - why are snap and flatpak a thing at all if source packages are good enough? Why do users want programs to get picked up as part of a distro's repositories?
That's Okay. What I meant was just reorganizing an OS and its nonessential apps repository/ies into 2 (or more) separate projects, not making a repository compatible with every distro out there.
How would that solve the issue of keeping repositories in a both well-tested and up-to-date state? It seems to me it would only make the problem worse because we'd have different, possibly incompatible or unmaintained PPAs
