I want to install the KDE clipboard manager, klipper, which is available under libsForQt5.plasma-workspace which provides a bunch of packages under KDE. Since I’m not using KDE, is there any way to install and use klipper without installing a massive bunch of packages?
Nope, but you could create a new derivation based on plasma-workspace that just copied over what you need or if it is possible changes the compile flags to only build klipper.