They have all of that. Flatpack is not a thing in Unix and you wouldn’t want it. If you want the terribleness of Flatpack stay on Linux. This post is about self-hosting not Desktop software.

Flatpaks, from the source if available, are excellent: you get the latest versions of the app from the official source, with permissions set for a pretty locked-down sandbox.

What’s not to like, I’m curious?

The storage is cheap these days, if you consider downloads are large. Core apps are robust.