Talking about turn-by-turn…. how is that implemented? Do you need to have premade GPX? Does DMD2 have a built in routing engine or is it dependent on a online routing engine?
OsmAnd is a very good and powerful offline navigation app, with offline routing engine. But I guess you are familiar with it.
Will DMD2 be able to use the same map files as OsmAnd if you set OsmAnd to use the shared storage on the device? I am asking since both DMD2 and OsmAnd are using Open Street Maps. This way you would avoid having duplicates of the maps.
OsmAnd has an API for integration with other apps. This could maybe simplify map downloads, route calculation, GPX generation and other tasks? The only downside I see is that OsmAnd has to be installed alongside DMD2.
OsmAnd has a demo app for the API where you can test some of it.
Just to be clear: this is a local API in the OsmAnd app, not an online API on the internet.