Note:
I understand “GPS tracking app” (at least now) as a business idea. So the information on this page is at first for this purpose.
See also Glomus
GPS tracking app with a map view (competitor app for e.g. “Geo Tracker” by Ilya Bogdanovich).
https://play.google.com/store/apps/details?id=com.ilyabogdanovich.geotracker
A GPS tracking app by Ilya Bogdanovich.
https://play.google.com/store/apps/details?id=com.gurtam.wiatag
A GPS tracking app by Gurtam.