If you want to have GrapheneOS do NOT follow their recommendations.

Do not use webinstaller!
Download the image of OS using Tor.
Disable all connections to Graphene's home. (connectivity checks, clock, supl etc)
Disable auto updates.
Disable App.

GrapheneOS is a terrible choice when it comes to privacy and personal security (fingerprinting) if you follow their recommendations.

DivestOS with pixel is an option to consider.