From my understanding what you mentioned is downstream from execution commands / CPU.
Theres no way for Google or any other service to reach those modules unless you give it permission on Graphene.
Discussion
Unless it's the modem itself. Which is connected... by definition. But that is true for almost every modem you can buy.
Your modem can leak IP addressing correct?
That's the risk here?
Not really search history or other logs?
That and some information about the device, which IPs it is accessing and so on. A malicious firmware can periodically ping any server without the user knowing, which would allow the server to triangulate the phone via cell towers.
Great,
So if this is your threat models just never use it at home - put it in a faraday bag & buy the pixel with cash.
Correct. But if you are at that level, I would also make sure there are no other electronics in your house. Anything can have a hidden modem these days, even your fridge.