Dumdum That depends entirely on whether Graphene updates the same way as Stock does.
So far that has not been the case. So far all devices that are not EOL receive the same version of GrapheneOS.
I am aware of these exceptions:
- When released, the Pixel 8 series was behind for around a month, because of a glitch in Google's release process.
- At present the project is issuing "legacy extended support" releases from time to time for various devices. But my understanding is that the project plans to stop doing that soon, so that instead of trying to support some devices on A13, some on A14, and some on A15, eventually all devices receiving updates will be on the same Android release.
Please note that I do not speak for the GrapheneOS project. I don't know when the project might stop releasing updates for various devices (though I suspect it may turn out to be soon for the Pixel 4 and Pixel 4 XL, and maybe also the Pixel 4a). I suspect the labor to maintain the older devices is increasing, and I suspect the number of users is dropping.