That sounds pretty cool, it's great you keep trying to improve the project. I'm also currently looking at other options to gather my fitness data, Health Connect, Samsung Health, and others. That could be useful for many other fitness rewards app. Of course, as usual with me, it will probably lead to nowhere very fast...
Strava is a good starting point, but that would neglect all the 'useless' steps from random daily activities, and believe it or not, some days it's a good chunk of my total count.
!ALIVE
!WINE