Would it be possible to create a feature that shows the graphics twice on one screen? It would then be possible to use a phone as an external monitor and use a cheap VR headset to simulate using FPV goggles.
That would be possible. I have actually plans to look into Google Cardboard support, but I have been to busy to get into that right now.
(For now, it is possible to modify a cheap VR headset by removing any internal divider and putting in a single large fresnel lens instead of the two separate lenses. That way you get the entire picture, like you would in box-type FPV goggles. I guess it is a bit overkill for most people to go through that trouble though).