The (pun ahead) peak of this method imho is implemented in "PeakFinder", afaik uses a low res nation wide (switzerland) height map, after initial gps fix it downloads local high res height map, calculates peak contours based of current location AND height and overlays that grid including the peak names onto the camera feed using the gyro and compass.

It's quite easy to build accurate geo-related applications in Switzerland due to the excellent work of the government office "Swiss Topo" that maps every tree, every house, every road in the whole country. Trees in cities have metadata such as: year planted, type etc. :)

Johnny Harris, the map aficionado mentioned Swiss maps and Swiss Topo's dedication multiple times in his videos.