It would be really nice if the KDE Neon Developer container came with all of the dependencies and libraries needed to build most KDE software. I was just able to build KCalc from source following this tutorial, but only after the build failed multiple times due to missing dependencies I had to manually install. Even running sudo apt build-dep kcalc didn’t catch all of them; I had to search online for the last one, which was libmpc-dev (I’m a bit new and didn’t realize at first that GNU MPC would have that package name).
If I were to be emotional for a moment, it was a really frustrating experience. Perhaps this is normal in any sort of software dev but I really just wish all of the dependencies were automatically handled.