Your probably don’t. I have a set of hubs with DTSwiss ceramic bearings (I think they may have the same source) that have never needed anything after years of everything. I bought the hubs used, and it seemed like the person who sold them to me was an insanely clean person who wrecked the donate wheels. In my case, they can survive snow, salt, rain, years of use, and a crazy clean person sanitizing them.
I bought SRAMs ceramic grease, but couldn’t even get the seal off when I went to grease them. Anyway, I heard decent ceramic bearing happen to last forever in the real world and I believe it.