What's the shortcut key for the Vertex, edge, face, pie menu? (not the 1,2,3 keys)
There isn't one in the built in pie menus. Viewport Pie Menus lists all of the available Pie menus.
There are third party add-ons, such as Pie Menus Plus, that add additional pie menus, including the one you're looking for. You have to check the documentation for the particular add-on to see what keys it maps.