APM Trigger Output Port

APM has the ability send an output (camera trigger) from its waypoint, actions, and navigation portion.

Does anyone know what signal or cmd it outputs and what pin(s) or port the output comes through on the navio?

The pin can be probably specified in the parameters, as well as impulse active level and length.
On Navio+ you can use AUX pin for that (it’s near the PPM Input) - it’s a GPIO 12.