It would be more streamlined list of my inventory if I could view Parents (Expandable to children) and 'non-variant' items all at once. It would also be helpful at this time when I'm creating listings en masse.
I do this using item categories. I've called them "Pack SKU" vs "Item SKU" but you could, if needed, do this with an extended property too?
For composite parents, you could use a filter for "Minimum Level" = -1
These aren't robust solutions though and there should probably be an easier way to see these things e.g. item is composite parent