Like a ‘One Shot’ ?
How about a suitable network delay ‘time constant’ feeding back to each other on 2 adjacent spare GPIO pins wired together so it sort of chases it’s own tail like a Flip Flop ?
When adjacent pins are Hi/Lo opposed in one direction for x seconds it could turn on a good old transistor (BC337 / 800mA drives most relays ) Or even an Opto / Solid state relay to be kinder to the Pi. This would rely on the loop time of Cayenne
A single GPIO pin going high could activate a relay or charge via an Opto device for a few 100’s of mS just when the single pin is made 'Hi’as a Capacitor charges via a Resistor and then self turns off (safely) once Cap is charged rather than above relying on a 100% reliable network and software.
Or some CxR time constant Monostable between 2 pins at least… May work using the Pi input pins with an inverted logic. May try this some time
However I too am hanging out for something like a python sand box.
Enable some cross pollination between Cayenne and the WebIOPi system engine room ? This is already well documented and organised with good wiki, tutorials already.
There is a lot more in there and some great functionality that could be wired across to Cayenne. E.g. have a few digital states and variables that can be Got / Put or otherwise linked as internal variables to the dashboard to and from WebIOPi.