Google could snap its fingers tomorrow and lock down the ability to unlock bootloaders.
This could prevent my next phone from being a Pixel.
But to be clear, there's nothing Google can do to my already unlocked phone running free (as in freedom) software.
I am already outside their walled garden, running a phone that will comfortably outlast all of the vendor locked ones receiving enshittification updates.
Now, I agree that the long term future of GrapheneOS, if it has one, probably isn't Google hardware. I find that Google doesn't present themselves, on the whole, as a trustworthy ally to free computing.
But for today, it kicks ass.