I don't think there is any direct claim for this. But you will find lots of old research about optical flow measurement for navigation. Optical flow sensor part of https://en.wikipedia.org/wiki/Optical_flow seems like a good start.
Satellite guided approaches are used when there is no visibility, so I don't know how that would help. You could use terrain-matching radar for navigation, but that would require additional equipment on the airplane. Every plane already has GNSS receivers, so implementing RNAV is basically a software feature.