I’m trying to find a work-around for connecting my Nest thermostat to HA. It may not be the cleanest method but it might just work. Since my thermostat is connected to Google Assistant and HA is connected to Google Assistant, can I use HA to send commands and receive data through Google Assistant to control my thermostat?
I don’t think you can do this with the Google assistant integration but I know that you can use something like Relay Assistant.
Relay assistant is basically an add-on which connects to your Google account and you can send commands to Google assistant. For example you can send “broadcast dinner is ready” through relay assistant and it will broadcast dinner is ready to your Google assistant devices. So in your case you can send commands such as “decrease the thermostat temperature” to decrease the temperature on the nest and so on. I am not sure how you can integrate this into Lovelace though, maybe use custom button cards with special services
Here is a nice video to get you started. How-To: Home Assistant TALK TO Google Assistant / Google Home - YouTube