> I've eyed KDE Plasma which could give me everything I ever wanted from a DE, but I was using Ubuntu/gnome because it was mainstream enough that everything just works OOTB
I'm curious, what do you expect won't work under KDE?
Nothing in particular; maybe third-party apps like MS Teams (ugh) I need for my customer projects (which also didn't work right on gnome for years, and had trouble when switching logins/customers), that kind of stuff. I considered kubuntu, but thought I was leaving Ubuntu mainstream for good anyway, so why not go to eg Slackware w/ KDE Plasma and say goodbye to systemd, snaps, and containerized browser behemoths that want to update themselves all the time anyway. Don't want that shit on my main machine period. I'll be keeping my old (Ubuntu 16.04 ESM and 20.04 LTS) notebooks around just in case, but customers keep sending me shite notebooks, and MacBooks are more than capable to run Docker crap anyway.
I'm curious, what do you expect won't work under KDE?