There was a mass resignation of expat pilots back in 2015 due to the airline imposing a pay cut. This thread from back then gives an insight into what went on.
Air Niugini T & C's
The B787 and A220 are fairly sophisticated types and require a decent amount of support to keep them in the air. The B787 has presented a few challenges to major first world airlines and could prove difficult for a third world country like PNG to operate. The engineering back up required is far greater than the simple and robust Fokkers needed. There will probably be a few well paid expat engineer jobs going when the aircraft arrive.