CalyxOS was not a hardened OS and is a much different space from GrapheneOS. It hasn't provided the 2025-06-05 or later Android security patches and updates for it have been discontinued. It's strange to recommend people use an insecure and non-private OS without updates.

https://calyxos.org/news/2025/08/01/a-letter-to-our-communit...

https://eylenburg.github.io/android_comparison.htm has a high quality comparison of the privacy and security between different alternate AOSP-based operating systems.