Flatpak makes no sense for Solus. I agree with an OS/App separation (I've been going on about it since before XDG App was ever a thing, and presented the original concepts...) - but Flatpak goes too far.
It replaces entire system runtimes, and system applications too. To me, this is unacceptable. We also then need to rely on third parties to maintain
these runtimes, and then somehow justify Solus as being maintained and secure.
Using these watered down runtimes on Solus would have detrimental effects: Solus is highly optimized, these runtimes will be generic for use
between other distributions, who have a hard time packaging (We don't)
Also Flatpak argues the OS can't be trusted, which makes no sense. Arbitrary applications cannot be trusted, the OS should have trust, otherwise
why is it being used? And if the apps aren't secure why are they being packaged? There's lots of glossing over the details as this particular cabal
run themselves into their poor recreation of Android on their mission to destroy the traditional distribution.
Solus isn't a traditional distribution and doesn't suffer the limitations being addressed by these other systems - so to be totally blunt XDG App/Flatpak
has zero relevance to us. I know people will say "But firefox is flatpak now!" - we build our own, and it's *integrated* and optimized, offering a
superior experience than something using different versions of GTK and potentially mixed themes and not able to connect to the host OS properly.
I'm not buying into that world, I'll carry on with what I'm doing.