Trimble TerraFlex has nested feature collection, something that is very helpful during larger field programs.
Nesting allows users to begin collecting, say an excavation boundary as a polygon. They start walking the excavation wall and then decide they want to add a wall sample. Instead of forcing the polygon to close when its geometry is incomplete, the user can simply open create a new point feature from inside the polygon form. This is called nesting and it would be helpful to add to both FieldMaps and Survey123.
Nesting is summarized on page 40 of this PDF:
https://plimgis.wordpress.com/wp-content/uploads/2019/01/terraflex-using-the-online-interface.pdf
