Have you enough to start looking at GSX for MSFS, or are you restrained too much right now due to the SDK as it currently is?
Even when the SDK was limited, we made lot of preparation work, to port our script engine to MSFS and to read MSFS scenery files and the latest SDK now allow us to create ground vehicles.
We are still missing some features, like creation of interactive menus, which has been confirmed to be coming in future upgrades, and we would rather wait to have it because, even if we could create a menu using other means, it would be less integrated in the sim and won't work in VR for example so, better wait to have proper support.