When Will Feature Sets be Supported in Portal Map Viewer?

[MegMaps000]

Hi all - I'm building a simple validation application for a client in Experience Builder. I need to implement an editing workflow to automate updating attributes in one layer taken from another layer when snapping to a feature in the EB Edit Widget (much like the current capabilities with the Smart Editor Widget in WAB).

I can't get this functionality working by using Calculated Expressions in Map Viewer as 'Feature Sets' are not supported in Map Viewer. 

Does anyone know when Feature Sets will be supported in Portal Map Viewer? Or a workaround in Arcade where I don't need to use Feature Sets so I can implement my snapping workflow?

I know Feature Sets are supported in AGOL, but my client isn't a heavy AGOL user and I'd prefer to keep the app in Portal. 

[SteveCole]

Hopefully someone from ESRI can chime in but, speaking in generalities, if a feature exists in AGOL and isn't present in Portal, you generally have about a 6 month delay for it to appear in Portal. I can't find a link off the top of my head but ESRI has discussed feature rollout in the past and said that the order of release is AGOL -> Developer Edition -> Enterprise.