Compilation of the plug-in went OK.
It is also recognized without any issues in GIMP 2.10. Now the title bar says “G’MIC 2.2.3_pre for GIMP 2.10”, which is nice. The main difference is that version uses the new plug-in API of GIMP 2.10 for managing input/outputs, so it works with high-bit depths images without quantizing them, contrary to the G’MIC plug-in for GIMP 2.8.
So right now, using this PPA, I don’t see any problems 