A custom HomeAssistant integration that creates an additional entity for each Google Device with a Fan "trait" such as a Nest Thermostat. This entity will track when the fan will shut off "In 2 hours 4 minutes" (rather than the 12 hours hard coded into the core Google Nest integration.
A service google_nest_fan.run_fan will also be created as an action to run fans for a custom duration.
The core Google Nest Integration must be configured and working for this integration to work.
The recommended way to install this is via HACS:
Add the intergration to Home Assistant:
If the core Google Nest integration is configured this integration should be able to configure your devices with fan and add the additional controls.
To activate the fan use the service. To stop the fan, simply turn off through the core integration. The sensor should display the stop time.