Google Pixel

Wrong, aside from the fact you should have been the one to install Graphene, even if it came preinstalled, the first thing you should have done was wiped and reinstalled. Secondly, running a HV on Android aside from it being very hard to due, and making the phone run like complete shit which you'd 100% notice in usability and battery like, would require root access, which would mean failing verified boot AND leaving the bootloader unlocked. Then on top of that, there's the fact Graphene can audit itself to verify everything is OK, while that move does require a 2nd GrapheneOS device, it's completely unneeded because of all the other things above that.

You're being totally paranoid man. You're not Edward Snowden. There's no 3 letter agencies after you, no "malicious actors". You're not going to get better than GrapheneOS if you want to carry a smartphone, not a useable one at least. Grapehene has proven itself, EVEN as far as Snowden is concerned!