Hi Tim,
At the time this widget was developed, the pluggable widget API was not feature complete. And the maps widget only support static markers, on one single marker from context.
The API is continues in development and Mendix might add support for attributes data sources soon. However if the API is available does not mean it will update for the Native maps widget directly after, Keep track of the updates. Or create variant of the widget yourself. Have a look at source code web version of the maps widget https://github.com/mendix/widgets-resources/tree/master/packages-web/maps/src where you might discover how the future API might look like.
Cheers, Andries