https://github.com/iDescriptor/iDescriptor
Currently it supports AppImage, but Flatpak version will possibly be available in future: https://github.com/iDescriptor/iDescriptor/issues/1

https://github.com/iDescriptor/iDescriptor
Currently it supports AppImage, but Flatpak version will possibly be available in future: https://github.com/iDescriptor/iDescriptor/issues/1

I didn’t see anywhere about it being able to install/restore system images, I’m assuming it can do that given what it’s based on though.
This is the only thing I’d use it for, so it would be nice if it could do it.