I think privacy and security are orthogonal, and I'm not convinced that GrapheneOS does a lot more than LineageOS isn't already doing for me in the privacy aspect - some of graphene's touted features are geared towards being able to use google's services in a secure and moderately private manner, but I'd much rather not use them at all. Meanwhile, its security features complicate life a lot with no tangible benefit to me, as I don't have a threat model that makes it interesting. I find my own freedom to modify my device as easily and freely as possible (e.g. by properly rooting it) much more important than locking myself down in the name of security.