However you can get close.
- Map component.
OSM and the Map component do have some issues that are not a problem when using Google Maps.
The left image shows your destination (red marker) and the route. The right image shows the long journey from your start to the red marker.
OSM has difficulty finding the exact location you provide. That can be fixed by moving the start to a location on a road. When that is fixed, it will provide a turn by turn route. That is another problem, ORS provides every turn for each switch-back you will encounter and in the mountains there are a lot of switch-backs. 
Each switch back is a Point; there are so many points the app uses a huge amount of memory.
Complicating the problem it appears this works for Android but crashes ios (severe memory problem ??? or something else ???) Sorry, I can not test this.
- Google Maps
App Inventor does not have a Google Maps control. You might try this extension
I don't know if it would work for you as I have not tested it.
Probably not possible.
No idea. perhaps someone who uses ios will comment.
You might be able to use the GM extension to use it in your app.
- a possible alternative is to use a Bing map which might have more tile resolution
[FREE] BingMap extension (will be deprecated by Microsoft by June 30th, 2025)