If you had a Nest account linked with Flair, do not migrate your Nest account to a Google account. Migrating your Nest account will permanently disconnect your integrations between Flair (along with other products) and Nest. You will not be able to reverse this.
If you set up a Google Nest account after August 31, 2019, we will not be able to connect your Nest thermostat to your Flair System. We will instead set up your system in our compatibility mode for All Thermostats. That means we will adjust Smart Vents based on room temperature readings from the Puck, but we will not be able to communicate with your Nest, adjust setpoints, turn your heating or cooling on/off, or read your home/away from your thermostat.
Google Nest plans on adding some of this functionality to their Works with Google Assistant platform. We will adjust our Google Assistant integration as this functionality is added.