I started using GrapheneOS today and was able to install the official Google Camera app through Aurora store (the only good camera app for pixels imho).
As akc3n suggested in their comment, the installable sandboxed google play services fixes some of the compatibility issues that Graphene has had up till now.
Obviously it's a tradeoff I'm making between privacy and a great camera, but I'm not logged into my google account anywhere and I denied location permissions to the camera.