Simple question, complicated answer. Yes, using the GPIO pins you could get the pi to know the pump is on manually. Now what to do with that signal? If you want all the zones to shut down, that’s one item you’d have to write/update in the python ospi service. If you want to ‘suspend’ the zone, then pick up from where you left off, that’s way more complicated. When a program starts, it writes the start and end times into variables. You’ll have to start a separate timer from when the pool pump started to when it’s shut off, then go through those variables, add the time, then start the service as normal again. Problems you’ll run into are what if a program hasn’t started yet, but does after pool boy is there? What if one program has started (and is now suspended), then another one is set to start before pool boy is finished? I’m sure there are other situations, but you get the point. How would you update the logging for times the zones ran vs. suspended? Yes, it can be done, but a you can start to see, it won’t be simple.
Maybe an easier solution would be to make the pool it’s own zone. I would expose a ‘Pool Fill’ button on a simple web page accessed on an internal ip (I’m assuming your pool boy has a smart phone). That button click calls the webservice to stop all programs, then starts the ‘pool’ zone in manual mode. Click the button again, and the zone is shut off. Or just give the pool boy access to your sprinkler webpage. Let him click into manual mode, stop anything that is currently running, start and stop the ‘pool’ zone manually.
Good luck!