which is controlled by Google
That's not correct. GrepheneOS is based on AOSP and not Googles version of the software. Graphene have full control over everything that they add or remove in their version as it is open source. They don't need to worry really about how google restricts apps etc. But the app developers may have to create a non google compliant version or refuse to. But the same may apply to SailfishOS. As mentioned here, they will now likely be building their own device trees, but the Motorola partnership may actually help with that.
Saying that, this is a Buy European community, and Jolla is the only European independent smartphone available, so they could never be regulated by restrictions that may apply to devices built outside Europe. That's not to say that (for example) US big tech lobbying in the EU couldn't affect them, and remove any privacy. But not something that we need to worry about right now.