Not an expert, but I recently heard that apparently not everything is perfect in fairphone land: https://discuss.grapheneos.org/d/24134-devices-lacking-stand...
Seems you have to compromise on HW openness and ethics vs paranoia.
I really would like to mention that many times, using /e/OS or LineageOS (or the likes) means that you get worse security than Stock Android.
It would be fine to run /e/OS or LineageOS on a Pixel, assuming those Android systems are not too slow with updates (my experience with my /e/OS phone was that they were 4 years behind as compared to Stock Android).
But really, if you have a Pixel, it doesn't really make sense to use something other than GrapheneOS IMO.
So to me it's really:
- GrapheneOS if you can
- Stock Android vs an alternative otherwise