[colordrops]

I do use a fake VPN blocker, and that's how I found out that you can't do it. You can either block completely, or you have to allow background network. There needs to be a "only allow data while in foreground" but google is a sociopathic company (as are most public companies) and wouldn't do something like this that is user friendly but revenue unfriendly.

[NotPavlovsDog]

As you outline, only a partial blocking is possible when google services and applications are on the phone (today this includes most apps from the g-store).

A "pure" analytics service may be blocked when reaching to a known spyware server. Bundled spyware and telemetry (is that "google core") are unfortunately not blocked.