I'm not exactly sure what I think about Flatpak and Flathub.
On the one hand, packaging and package maintenance is a huge burden for distro developers. The dominance of systemd, Wayland, GNOME and Electron pushes for isomorphism (in the sociological sense) and distros today are not as different as they used to be. This means, lots of effort is wasted, especially when all the distros that ship a certain application place it under /usr, don't carry any patches, use glibc, and so on. A reliable cross-distro package manager makes life easier for both developers and users.
But, on the other hand, the Flatpak SDK is essentially 80% of a separate distro, stuffed in a chroot environment: it's huge, and the responsibility (and authority) to push security and stability fixes is more centralized than ever. In some sense, this "vendor-neutral distro" is a single point of failure. In addition, Flatpak supports what many consider to be erosion of free software UI, through CSD, per-application GTK+ themes, etc'. Flatpak brings applications closer to the lowest common denominator among distros, and that means the SDK contains older libraries, uses the default GTK+ theme, and so on.
However, it looks like Flatpak is the future of Linux applications (at least, interactive ones), and it's an easy way to try out an application. Therefore, despite my ambivalent feelings about Flatpak (and AppStream, and other things), I hope to have gplaces in Flathub soon. Yes, a 100K application that depends on an SDK that weighs hundreds of MBs.
ID Branch Op Remote Download
1. [|] org.freedesktop.Platform.GL.default 21.08 i flathub 12.5 MB / 131.3 MB
2. [ ] org.freedesktop.Platform.Locale 21.08 i flathub < 325.8 MB (partial)
3. [ ] org.freedesktop.Platform.openh264 2.0 i flathub < 1.5 MB
ID Branch Op Remote Download
1. [\] org.freedesktop.Platform.GL.default 21.08 i flathub 15.0 MB / 131.3 MB
2. [ ] org.freedesktop.Platform.Locale 21.08 i flathub < 325.8 MB (partial)
3. [ ] org.freedesktop.Platform.openh264 2.0 i flathub < 1.5 MB
4. [ ] org.freedesktop.Platform 21.08 i flathub < 199.7 MB
5. [ ] com.github.dimkr.gplaces test i gplaces-origin < 47.0 kB
Installing 1/5… █████▏ 26% 568.2 kB/s 02:10