Calyx is unfortunately pretty slow to release security patches, uses privileged apps with root access like microG and the F-Droid privileged extension by default and doesn't really provide any unique features. All of the privacy features of Calyx are either already present or can be easily replicated in a better form on GrapheneOS. Take Datura Firewall, it's yet another privileged app with root access which adds unnecessary attack surface, and is less secure than the Graphene equivalent. GrapheneOS implements a network permission toggle, which is embedded in Android's native permission manager and uses the INTERNET permission to restrict network access. It disables both direct and indirect network access, including the local device network (localhost). GrapheneOS also has a bunch of unique security features, that can't be found on any other Android ROM, like for example a hardened memory allocator, hardened kernel, secure app spawning, improved SELInux policies, Duress PIN/Password, driver-level USB-C control, Storage Scopes, Contact Scopes and soon App Communication Scopes. GrapheneOS also includes Sandboxed Google Play services, a better GMS implementation than microG, which doesn't require root and has better app compatibility.