Currently AGOL vector tile layers don't seem to support popups/legend items so our internal webmap users have to go to secondary information sources to find the symbology meanings, in our case building zone information. In the current case we are consuming an external layer that is only published as vector tile, so there does not seem to be a second option. We will look at working around this, but it would be good if this can be supported where possible; although I realise that vector tiles are very different in nature to map or feature services.
