I have the Nest Integration working with my personal developer keys.
The integration appears to work well if controlled from within Hubitat.
However, when I link the Hubitat Nest Thermostat device to Google Home, I can't get it to work. I can of course link the Google Home directly to Nest, but would prefer to have all devices controlled through Hubitat.
When the link to the Nest Thermostat is created between Hubitat and Google Home, it appears I can control the operating mode. Also IF the mode is set to auto, I can control the setpoint. However, if the mode is Heat, I cannot control the setpoint.
Just a guess without seeing the code in the background - I think when it is set to Auto, Google Home sends commands separately to the heating and cooling setpoints, which Hubitat accepts. However, I think when it is in Heating or Cooling mode, Google Home is sending a command to the general "thermostat setpoint", which Hubitat is not accepting.