Flatpak is probably the best way to distribute desktop apps on Linux. I say this as an app dev, a packager, and a user. At one point I maintained close to a dozen packages.
I eagerly waited for months to see what they would do next - what magical features they would introduce. I was active on the forums helping other users package apps, helped review Flathub submissions (since it was always the same problems each time), and started checking out what PRs were happening. Silence.
The months turned into years, and as more years came, I slowly fell away from engaging with Flatpak. I'm back to using the AUR for most things (Arch, btw), but I'm quite sad to hear the situation get spelt out. Flatpak really was revolutionary; bringing modern apps and painless distribution to all desktops - LTS or rolling release. But it hasn't really changed at all since it first took off years ago.