Maybe I jumped to conclusions. Being listed above is rather upsetting, as you might imagine.
It's not a GPS-enhancing app, it's a physical device, the Garmin GLO 2 at the moment. It connects to any bluetooth device (a phone or tablet, but I've used devices like it in various field vehicles for work) and interfaces with an app which Android uses as an alternative source of GPS info. The app can control the sampling rate, etc. Because it's a bluetooth connection, the device's location must be within meters of the phone... but really it's in my pocket.
The Garmin has it's own app in