Does ArcGIS Experience Builder or ArcGIS Dashboards have (or plan to have) a multi-level dropdown layer selector widget?
This multi-level selector allows users to switch between different layers. This selector is different from the selector on the Dashboard. The selector on the Dashboard filters the same layer.
The out of the box widgets for Experience Builder are rather slim at the moment, but I think it is possible for you to create a custom layer list widget that will do what you are looking for. Check out some of these examples https://github.com/Esri/arcgis-experience-builder-sdk-resources/tree/master/widgets