I know there is an AppImage but I prefer the convenience of flatpak. Had anybody tried to make an Rawtherapee flatpak on top of the Gimp flatpak? So you can still use Gimp. I would like volunteer to provide the build recipe to flathub if the developers see any value in it.
I’ve made one and there is another one floating around on github. There is a PR open for one with flathub. Not sure why they haven’t accepted it yet. https://github.com/flathub/flathub/pull/789
However, if you’d like to flatpak some other software: Rapid Photo Downloaded, HDRMerge, Luminance HDR, or any others would be awesome.
Do you thought about to extend org.gim.Gimp.yaml? So gimp would be in the flatpak too but if you install the gimp flatpak you would share the HD space.