I think people sometimes grotesquely overestimate what level of "privacy" they can get on a device connected to networks and the internet.
Yes, you can make it harder to be tracked by advertisers and other third parties.
But tracking and surveillance isn't tied to the hardware and/or software, it's mostly about the content you publish.
You can use tor on a public network with a stolen device from some stranger, but you will be identifiable through the style of writing, everyone has patterns in the way we communicate and the habits like what we are interested in, what we search for and how, even the times we go online are mostly repetitive and follow personal habits.
If you want privacy, don't use the internet and don't use mobile devices. You can't eat the cake without leaving crumbles.
Graphene can minimize much about the constant surveillance, but still, there remains surveillance.
Sometimes i think people don't want to realize that they would have to sacrifice using the internet to become a private citizen again. Though it offers some nice convenience, it's probably the most disruptive technology we ever used.
Using less internet is good for you and your privacy.