For mortals, using XMonad under KDE seems to require a little work. On NixOS, though, it looks like XMonad can be enabled with a single config line:
I’m imagining I would put that right next to these, which are already in my config file to enable KDE:
services.xserver.displayManager.sddm.enable = true;
services.xserver.desktopManager.plasma5.enable = true;
Will doing that in fact replace Plasma’s default KWin with XMonad? Is it really that easy, or should I expect conflicts to ensue?