Geoff_T
Yes, technically it should work on any Android, but currently indeed as low as Android 10.
At first I was targeting a minimum SDK of 8.1 (27) as the older FYT SC9853i and cheap 8514 units run 8.1. All newer ones and "more expensive" ones run Android 10 or above. However, the 8.1 required a different overlay functionality and I didn't want to make it too complex by supporting two routes on devices I don't even have anymore.
As far as I know Android 9 should not be a problem. I did set the SDK from 29 (10) to 28 (9) in my build file and simply ran a compilation. It compiled without issues. Of course I didn't test it (couldn't test it). I did send you a Google Drive link in a Gmail PM. Please try.
Note to others: Nothing has changed or fixed. This is simply a recompilation of the current 2.3.
(I said I was busy with moving to another house. That has still not finished, but I needed some distraction, so I built MapPlayer)