I like Calyx quite a bit. It’s considerably more private than any stock Android out there. However, from my perspective, GrapheneOS is the best mobile os out there for security and privacy too, hands down.

I run GrapheneOS on my Pixel 8 Pro, tried Calyx back when I had the 6 Pro, and it pretty good and everything basically works, but GrapheneOS from the beginning is so vanilla, only has a couple of apps installed (phone, sms, Calc, files and such), everything else you need to choose to install.