Flatpak is actually made by the same groups of people who make these open source DEs, as well as the various open source stacks we use on the desktop, it’s had the advantage that it’s integration into the desktop is decent and quite cool (hello pipewire).

Regardless of your opinions of GNOME and KDE, it’s hard to argue Flatpak has anything but good intentions, it’s made by people who want the Linux desktop to be better