Maybe just starting point, but some diagrams were made available in the following post, and the pinouts two post above the latter.
More exhaustive pinouts list:
https://github.com/FrameworkComputer/Mainboard/blob/main/Electrical/Pinouts.md
Did not have much time to check it myself, but you might get lucky and find what you are looking for in this https://github.com/FrameworkComputer.
Hope it helps.