For purposes of ease you can consider the wiring to be a 24v PS powering the duet with an e-stop on the 110v AC hot line to the Powersupply. All voltages have been tested and are stable and good.
Powersupply is Meanwell, not a shoddy no name brand.
Reason for simplifying wiring explanation (https://photos.app.goo.gl/xwvkHzTZuaX2JA2P6) Don't judge not fully wire-managed yet
The SBC currently powered via a 110v to 5v 3A USB-c "wall wart"; to be changed to a dedicated 5v powersupply once I rebuild the cable between duet3 and Pi.
The Duet only has the Internal 5v Enable jumper set: i.e. SBC -> 5v, and 5v -> SBC and not jumpered.
I am using the cable sent with the Duet3 for interboard communications.
Will get M122 and enable monitoring and get some thing uploaded shortly.