I went through something similar just trying to get my NEST to work in home assistant, thanks to HA these are the well documented steps, and each step has multi

I went through something similar just trying to get my NEST to work in home assistant, thanks to HA these are the well documented steps, and each step has multiple sub-steps... - Create and configure Cloud Project [Cloud Console] - Configure OAuth Consent screen [Cloud Console] - Configure OAuth Application Credentials [Cloud Console] - Create a Device Access Project [Device Access Console] - Enable events and Pub/Sub topic [Device Access & Cloud Console] - Link Google Account It ended up that the linking would not stay persistent, a waste of $5 and many hours.