Thanks! Yes its a shame that Debian (and Leap?) Will not have Plasma6 in like 6 months where stable release would fit perfectly.
My experience is the same, on Manjaro Plasma was way better than on Kubuntu and Manjaro convinced me of Plasma. Fedora is a sweet spot and staying with F39 for a while (even though I will probably switch to F40 right away as Plasma6 has sooo many bug fixes I personally reported) could work.
You mean a rootful Distrobox with a DE in it? I have to try that out, sounds crazy. Would need a seperate home if that is possible, as I dont want to have messed up dotfiles.