Bspamail What does google play services do with network access? What data goes to google?
I don't think anyone can answer that question definitively, and that's why some of us choose to avoid the Play Services and Store.
What we do know is that Play is used to provide punctual notifications for the many apps that rely on it via Firebase. For this to work properly, Play Services requires network access; the Play Store may require this as well, I don't know for sure.
Play can also be used to deliver ads to other apps that make use of it, even if those other apps don't have network permission. With that, I think it's safe to say that Play can collect a lot of usage metrics, both from Play itself, as well as from any app that ties into the many, many Play components (ads, analytics, etc).
Its usage depends on your threat model and privacy goals. For me, I only use GSF and without any permissions.