Python + OpenWRT + hardware buttons. How?

Question

linux

There is a scarf, already known to many (MR3020), there is OpenWRT on it. There is a need to handle pressing hardware buttons (for example, WPS) on it.
On a piece of iron, Python code is spinning, and I would like something like interrupt handling for these buttons. That is, the user clicked - the function was executed.
This is the main problem. You can hang the script execution on this button, but you need to send this event to the running code.
Who can suggest what?
So far, the only thought is still to hang a script on the button that will send, for example , SIGUSR1 to the process :