Kind of related to this Idea, and a way I think it could probably be implemented. Create Buffer/Geofence Around Points in Field Maps - Esri Community
In short, I would like Map Viewer to have a group layer tempate.
In Pro, you can use group templates to create multiple associated features from different layers at once.


I would like to do this in AGOL (and then in FieldMaps) to speed up the editing process, as well as do some of our data processing in advance; no need to manually buffer when you can populate the associated feature class automatically when you place the site.