I am working on getting GeoJSON (and probably any other supported type) support into the widget. As soon as I get some elementary example working, it would be great if we can start testing the code. I do expect bugs in handling adding/updating/removing items. That would be great if you could test on desktop and we can address issues one-by-one. But to get there, I need to finish the code that we can test and write documentation for each method that needs it.

Additional help would be reading what is actually possible. I am new to Mapbox GL and I am learning by doing this interface. I wouldn't be surprised if many of MartinK requests are already supported via Mapbox GL. Not that you have to rewrite the docs, but help when we get requests on whether one or another thing is possible and help to write simple-to-use wrappers that map applications can use (add route, position marker, pois, ...)