> I guess they are not entirely on Google Cloud but rather their data warehousing / big data stuff is now?/going? to be on GCP.
I don't know why you would guess that: the Google announcement indicates that the migration has both a "services" track and a "data" track. And Spotify's announcement certainly seems to indicate that they are moving off of their own datacenters, onto Google Cloud Platform, and not in a limited way.
So... basically nothing is live yet? Are you from Google? Is anything live. I admit I got confused by the OP title: "Spotify moves its back end to Google Cloud".
I don't know why you would guess that: the Google announcement indicates that the migration has both a "services" track and a "data" track. And Spotify's announcement certainly seems to indicate that they are moving off of their own datacenters, onto Google Cloud Platform, and not in a limited way.