I admire this effort. However I don't care that much about my privacy and I don't care about extended security. All I want is a basic Android system without any of added apps, without any AI. I want the most basic apps for phone, SMS, camera. And I want working Google Play to install some additional apps. I want OS focused around this goal. Not OS focused around extended security or privacy.
So it's like suggesting to buy M1 Abrams instead of Toyota Land Cruiser.
I'm embracing ascetic computing. I'm using Arch Linux with bare minimum of apps for my desktop. And I wanted to do the same for my smartphone. Pixel is incredibly bloated. I spent few days just navigating its maze of settings, trying to disable them all. At this point, I'm back to my old iPhone, which at least allows me to uninstall almost every single app and old enough, so it does not support Apple Intelligence (thank, god).
Its similar to what the Linux distributions that try to turn on a SeLinux like profile by default would feel like if they really put in the work. That's nothing like switching (from a Linux) to a BSD.
(I would love to just run my desktop Linux with a half baked touch UI and rely on browser versions of almost everything, but that would feel like a real switch between OSes instead of just seeing the same OS with a corrected security profile as the user. I also don't see why you compare it to an Abrams, I doubt an Abrams has a security model intentionally compromised by an ad company, GrapheneOS just makes it possible to catch the dumbest or laziest attacks on a system no one should run ever.)