Grapheneos with Google play services (sandboxed) only send 12 packets per hour, instead of around 350.

That’s great, but the sandboxed Google play services are by default set to normal in battery usage. Meaning it’s subject to dooze and other ways to artificially limit its background activity.

You neee to set the battery usage to unrestricted to reliably revive notification.

I wonder what the packet count would have been with unrestricted Google play services.

I'm less interested in the quantity, and more in the content of those packets. Do they contain my GPS movement history? A list of installed and opened apps? My contacts list, messaging text log, and list of visited websites?

The data I really care about protecting would fit into a few kilobytes, so knowing the phone sends, for example, a minuscule 2 MB/day, brings me no comfort.