This tutorial uses the Map and FeatureCollection components to make a quiz about the New England states. Users click on the state when prompted with the state name or state capital. This is an example of using a GeoJSON file to add clickable polygon information to a map.
Here is the tutorial
If you'd like to see the completed project in App Inventor, download the source code
to your computer, then open App Inventor, go to the My Projects page, and choose Project | Import project (.aia) from my computer.
If you would like to download and view the GeoJson file used in this tutorial, click on this link.