Field mapping for copying/pasting features using Editor widget

Bud

I'm copying/pasting features from layer1 to layer2 using the Editor widget. I want to set up field mapping so that layer1 OBJECTIDs would be copied to a layer2 ORIGINAL_ID field.

Use Case: I want there to be a common ID between the two features so I can know what the layer1 source feature was for the layer2 destination feature.

Idea: Could field mapping functionality be added to the Experience Builder Editor widget for copy/pasting features?

Related AGOL Question: Auto-populate unique ID field in hosted feature layer (common ID between copy/pasted features in ExB) 

Bud

I wondered if I could set up an Arcade expression in the layer2 ORIGINAL_ID field, using form configuration in the web map. The expression would grab the OBJECTID from layer1. But I don't know how that would work, since the expression wouldn't know what layer1 feature to grab the OBJECTID from; there's no tabular relationship. I guess there is a spatial relationship, since the two points have the same location, but that seems pretty clunky. And that wouldn't work for geometry-less features or records in a non-spatial table.

I don't have any experience with Arcade expressions in form configuration. So I'm just guessing.