Is there a way to add items to the 3D Viewport Pie Menus

I want to be able to add my own addon to the menus that appear through the included 3D Viewport Pie Menus. Anyone got some pointers as to where I should look for documentation for the Pie Menus addon?

the following link from latest blender manual provides information about “3D Viewport Pie Menus”

https://docs.blender.org/manual/en/dev/addons/interface/viewport_pies.html#d-viewport-pie-menus

hope it helps.

I’m not sure about documentation but often it’s best to go directly to the source code:
Maybe you’re already digging into these?

There’s a basic template here:
./blender-git/blender/release/scripts/templates_py/ui_pie_menu.py

This looks like what you want:
./blender-git/blender/release/scripts/addons/space_view3d_pie_menus/

Good luck