The idea is to basically allow us to pin add-ons and extensions context menu actions to a sub-menu in the context menu itself, to avoid clutter from having too many context menu options.
At the risk of making this too complex, it might be nice to have there be a settings option for whether to put addon context items into a submenu or not. And in that case, it would be even nicer to choose which addons go into the submenu (i.e. so you could have your most-used extension items in the main context menu list, while your less-used extension items are in a submenu).