Exactly CalyxOS doesn’t provide anything that GrapheneOS does not. GrapheneOS simply is a better alternative so this should be the recommendation. If people chose not to follow that, that’s fine, but why recommend things that are not simply the best. Don’t make it more complex to the vistor just focus on good and easy solutions.
I am not even recommending CalyxOS for Fairphone. MicroG is a hit or miss and will mostly just limit your experience in a bad way.
DivestOS is there only because it has support for other devices as well and provides some hardening. I happily use this on a secondary device, but given there is no play services it for most people won’t be so useful.