Simple Add-on v2's specs are identical to SAOv169bis. The first pin is VCC, power, and it is expected to be 3.3 Volts. Second pin is Ground / Earth, third pin is SDA, fourth SCL, and the last two pins are for GPIO. The only two pins that are always expected to work are VCC and GND, the other pins are optional. If you are making an Add-on and would like to make use of Pins 3-6 you should coordinate that with Badge / Device makers or at least document it well so that badges that would like to accommodate that can do so.
As this standard remains compatible with the original "Shitty Add-on" standard it uses the same pinout. The supplied "SAOv2.zip" is a updated and renamed version of the original SAOv169bis KiCad Footprints and Libary files that I created in 2019. The changes made to the "SAOv2" part pertain to better dimensional accuracy and changing the square pad from "GND" to "Pin 1" which is VCC.
There are two foot prints provided for your use. The "Badge" Foot print has an outline of the Keyed Female part on the Front Silk screen and on the Back Silk Screen has the pinout labled. On the "SAO" Footprint the front is left completely blank while the back has labeled pins and an outline for the Male header.
As this standard remains compatible with the original "Shitty Add-on" standard it uses the exact same parts.
The Add-on board will use a Male 2x3 2.54mm (0.1") Pin Pitch Shield header and the Badge / Host board will use a 2x3 2.54mm (0.1") Pin Pitch Female connector. For mechanical security it is preferred that the female part use a Polarized Keyed part but a non-keyed connector will work.