To install grapheneOS on a pixel you literally have to just go to their website and click 3 buttons. It does all the heavy lifting for you with their browser based web installer:

https://grapheneos.org/install/web#web-install

Let me know if you have any questions!

People get pixels just to have Graphene and the best de-googled experience out there!

I came from LineageOS, and as good as that is, Graphene is superior and more "user friendly" for newbies to privacy upgrade lifestyle....