We build Flatpak bundles as part of our CI process, so you can even have downloadable app bundles to test per branch https://github.com/elementary/music/blob/d7fbb4fcff8be47f913a135945eaacb6873c0862/.github/workflows/ci.yml#L13
And then we deploy to our own remote also directly with GitHub actions: https://github.com/elementary/music/blob/d7fbb4fcff8be47f913a135945eaacb6873c0862/.github/workflows/release.yml#L30
Users can download flatpak reference files from your website or use https+flatpak links and install your app with just a couple clicks. No terminal. No adjusting permissions. No fiddling. Just works. Cross-platform app distribution on Linux is solved