My idea is to have the ability to edit map legends within Experience Builder.
An example would be, in ArcGIS Online your layer uses clusters when zoomed out but in the ExB you could select to only show the symbols and not all of the information about the cluster.
Also the ability to customize the layout of the legend like you can in ArcPro, being able to change the size of the symbols in the legend without changing the size of the symbology on the map. Selecting how you want the symbols and words laid out in the legend rather than a fixed style.
I also asked about this during the UC, hopefully this is an update we can see soon 🙂