Great job on the app, MIP! I have a suggestion.
Would the app work with a lower minSdkVersion? I'm worried that Android 6.0+ is probably not what most of the unbanked population have on their phone.
Furthermore, according to
https://developer.android.com/training/basics/supporting-devices/platforms , Google recommends as a good practice to support about 90% of the active devices, while targeting your app to the latest version (targetSdkVersion).
Here is a nice pie chart of the version distribution:
https://developer.android.com/about/dashboards/So 90%+ would include 4.4, but I know that's a drastic difference in OS, so if the app doesn't work on 4.4, maybe you could at least include 5.0-5.1, since the OS is basically the same as 6.0, so the app should work, and that would increase the app penetration by a whole 23%, which is around 500 million users more.
And probably a lot of the unbanked would be in that 500 mil.