I can't see the point in that? Certain tools could work fine, but the actual desktop environment? It'd be running in a sandbox and would need to be given access to everything to function presumably. The various tools need to communicate with each other and the X11 or Wayland composite. So the flatpak container would just be overhead with a lot of duplication of system libraries? I'm not even sure it's possible but I don't know enough of the limitations of flatpak.
It's an interesting idea to test and play wth but I can't see it as an actual viable means of distribution.
If you wanted to play with plasma 6 then Virtual box and KDE Neon or Arch would be the way, and would negate the work needed to to get it working via flatpak. So I guess what would be the benefit for anyone to build and test it via flatpak even if for feasible?
I mean as you can use far newer KDE applications on Debian stable via Flatpak, it may serve the same purpose contained in a separate tree without changing the core OS.
I guess distrobox+neon would work fine yes. I just wondered the state of Flatpak with the recent changes.
It will be isolated in its own directory, as I said I think distrobox.it+neon+, own home will be a far better solution of course. I keep hearing Flatpak is adding snap-like deeper features so I wondered how far it went.
About the KDE 6 being unstable: I think they wanted to ship something out and for people preferring stability, 5.x LTS will be there for a long time.