In case of the Argon40 addon it is used to observe the shutdown pin GPIO4 for an incoming pulse. This pulse will be generated by the MCU at the pcb of the Argon ONE if:
- Remote control power off command signal has been detected
- The power button at the back side of the case has been double tapped
- The power button at the back side of the case has been hold for 3 seconds at least, but shorter than 5 seconds
The pulse time for double tap is 20-30ms, for the other ones is 40-50ms. If one of these is detected by the addon, KODI and therefore the operating system will be informed by the addon immediately to initiate a reboot or a shutdown, depending of the mapped event to the pulse time. The shutdown signal is the more critical moment and cannot be skipped, as the MCU starts an internal timeout of approx. 10 seconds until it switches off the power - regardless of whether KODI/the operating system is ready or not. Additionally, KODI has an internal timeout until it tries to kill running threads after 5 seconds during process stopping. But this seems counterproductive in the case of the default Python modules lgpio and gpiozero (due to some bugs) and leads to a fixed timeout of 30 seconds for the KODI process.
That is the reason to have a library which is able to fast release the resources (below the KODI 5 seconds limit) to have mostly a properly shutdown.
EDIT:
Okay, after reading again. If you're thinking in terms of extending functionality using the GPIOs, it's up to you to find some real-world applications. Like rolling or unrolling canvases, triggering an actuator for a fire extinguisher above the housing or something like that. 