I develop location aware applications for mobile phones professionally and run into plenty of problems regarding GPS/compass inaccuracy on phones. As I was wondering about the accuracy of my forerunner 245 music, I decided to develop an app which sends the watches current GPS and compass status to my android phone over bluetooth and visualises it on a 'classic' google maps view.
Basically in the app you have the maps view with your phones 'location dot' as usual and there is a different color second location dot which displays your position and heading as your watch reports it.
It is now developed as a proof of concept for myself to use, but I was wondering if there is interest in something like this, as I may want to develop it further and put it up on the store.