I do not have Google Maps and instead use µg Unified Nlp with OSMand~ (both from F-Droid) and I got really surprised, when I was going by train and GPS showed my exact position on the rails. 
I do not have Google Maps and instead use µg Unified Nlp with OSMand~ (both from F-Droid) and I got really surprised, when I was going by train and GPS showed my exact position on the rails.