This is basically a service listening on a specified MQTT topic, to shut down the device when OFF is received.
This also includes means of setting the remote shutdown on hold or disabling it from the local machine if required.
The install script will place the python script, the systemd service file and configuration templates in the default locations. The OpenRC is included for legacy reasons, as I tried using that for a while, so it may not work in its current state.
Warning: The install script includes some hardcoded UID that should be changed. I did not come around to doing that.