Hello fellow GIS nerds! So I created this "Legend" concept using the Filter widget. (I gave the widget a different thumbnail image.) Our users like having this concept as a legend, because ...
Each item has a convenient on/off switch.
Unlike the "Layers" widget, you see the legend symbol without having to expand the layer. And it's nice and clean.
Expanding the layer allows the user query what features to see.
When you turn the switch on, the map zooms to whatever features are returned for that layer's query settings.
In order to make the on/off switch work the way we like, I have to "trick" the widget by putting a filter on the source layer in the source web map that filters out all records (e.g. OBJECTID = -1) ... Then I tell the Filter widget to override the layer's web map filter, whenever the layer is switched on.
It would be really cool to have a widget that allows users to set up their legends this way, but without having to use that trick.
The map in the above image is password-protected, so I won't link it here. But here is another (publicly-accessible) example of using the Filter widget as a legend: