This is not the same thing. My Chromecast dedicated device would put a default nice picture, then wait for a cast. Google TV and this new device displays advertisements, store, and more. I hate it. It's the last google thing in my house. When it dies, google will be gone from my house.
Honestly might disconnect the nest from the network. But only keep it connected and segmented from rest of network for remotely changing the temp from my phone.
One of these days I’ll “hack” (explore) the device so it doesn’t rely on Nest/Google APIs. There’s absolutely no reason why I need a Google auth token to access the Nest other than for Google to collect whatever data and feed to their beast