Couldn't you create an alternative to have a satellite view of the map (or a real image from above of all the buildings, similar to JAVA) and convert it into a good resolution image to enter into the game as a poster? It doesn't matter that it is not a real-time image of the game, we will be the players who will have to refresh it manually at will, for me that would be a good solution while a solution for a GPS map with satellite view is found. What I mean is that taking screenshots from above and putting together a map like a puzzle is not the same as having a real view from above as in JAVA
That would be a camera mode which is something Unity is capable of.