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First of all, welcome to the forums marcmarcdv!

The current GPS apps have been currently discussed before and it seems because of the SDK limitations, a voice, turn-by-turn navigation app is forbidden (so far). I would advise to search the forums for more info.
 
even witout voice TBT, I wish google maps could indicate by an arrow if your next turn is left or right so as to be in the right lane.
 
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