In an up-to-date KDE Neon, I tried to use `sudo apt build-dep plasma-discover` to install plasma-discover's dependencies so I could build it from git master. This installed almost all the required packages, but missed libkf5declarative-dev. After manually installing libkf5declarative-dev, I could build it.
https://packaging.neon.kde.org/plasma/plasma-discover.git/tree/debian/control?h=Neon/unstable&id=37b11bcdd876e6b8290fbb605172a0490d45e3a2#n22 I don't see how this could not be installed. The bdep is there for years.
Hmm, that's odd. I wonder why it didn't get installed. I'll try to reproduce this in a clean Neon VM.
Nate, what is the status of this bug?
Thanks for following up. Can't reproduce anymore with a clean checkout and environment.