Currently I only know that the sparkfun board (https://www.sparkfun.com/products/15136) has access to the pin, but it does not have on-board logging. I’ll be investigating if ardupilot is able to do the logging or not shortly. Unfortunately the ardusimple V1 boards do not have access to that EXT INT pin, so they will only be good to use for non-photogrammetric applications at the moment. They did note that V2 will have the feature. https://www.ardusimple.com/question/extint/
Looks like orders of the sparkfun boards just caused them to go out of stock (they had 15 in stock 24 hours ago).