I tested an KDE Neon LTS 5.8 (based on Ubuntu xenial) and KDE Neon 5.9 (based on Ubuntu zesty) on my system. With both distributions, nouveau and mesa glx is running fine. Also connecting with x2go to an x2goserver installed is no problem. After compiling and installing the mentioned latest NVIDIA driver, x2go fails again to launch KDE plasma.
Klaus