I have a Canadian carrier purchased phone. Brand new Pixel 9. 5$ a month. For 24 months.
It has only ONCE booted to the Google version of Android.
To flip the toggle to enable OEM unlock.
I kept WiFi off and hadn't inserted a SIM so it couldn't update or do anything else that might have prevented flashing graphene.
Not sure if that was necessary, but it worked.
And now I live my life free of google software surveillance.