Pixal proprietary software phoning home

Firesign

Question for the dev team.
First post and thank you for helping me to understand my pixal and grapheneos better.

I use next dns. When I check my next dns logs I can see the DoT and DoH communications from my pixal. This enables me to block certain domains/trackers etc.

Having also preset my pixal's Permissions within grapheneos, I am aware that certain Android system apps, e.g. Shell, cannot be prevented from using the Network Permission.

My concern is that my phone can still send my private data to third parties. If I can prevent this then I will.

I assume that these pixal system apps and proprietary software will phone home to their manufacturers.
Would this communication go via next dns so that I can block it?
Does grapheneos block these apps/software from phoning home by default? If no,
Is there any other way of preventing this communication?

Thank you for your time in responding.

Best,

[deleted]

Firesign https://grapheneos.org/faq#default-connections

Firesign

Thank you for the link.

It is my understanding based on the linked section below that no system apps or proprietary software can phone home if I select the graphene os servers (which I had already)
Is this correct?

You can change the connectivity check URLs via the Settings ➔ Network & Internet ➔ Internet connectivity check setting. At the moment, it can be toggled between the GrapheneOS servers (default), the standard Google servers used by billions of other Android devices or disabled.