Not OP. But I am using GrapheneOS for almost 4 months now. It is a breath of fresh air. Network Permission, Contact Scope, Duress PIN, Hardened Malloc, JIT tuning, Sandboxed Google Play etc.. are some key privacy and security features in Graphene. Will never go back to Apple's or Google's surveillance platforms.
Not OP either. It's quite "buggy" (honestly too many to list, mostly UI issues, app issues that can either be attributed to the OS or the app)...but overall I'm happy because of all the great features.
Android Auto works well for me on Graphene (Pixel 9 Pro) but I obv can't make GPay work given that it relies on the OS having Google's blessing and they are actively hostile to GOS as a project.