Pure ceramic is porous, so it is never used in direct contact with food, because the food will be absorbed in the pores.
In all cookware where the body is ceramic, the surface is covered with some glaze, enamel or plastic coating, which is the material that really counts for food contact.
You are right that unglazed pottery had been used for many thousands of years, before glazing was invented.
The information about soaking is interesting.
I was not aware of it, because there are many countries were unglazed pottery is no longer used, at least I have never seen any of it used for food contact, but only for different purposes.
> The problem with modern Teflon is mostly that people overheat their non-stick pans
Also using metal or other "hard" implements in those non-stick pots/pans, which damages the non-stick layer allowing it to flake away into the food prepared in it over time.
If someone responds that a material is 'chemically inert' when we're talking about heating things up, I don't think I'd have much confidence that it's not leaching into my food.
Not quite. Off-gassing begins at a bit under 400F. And the assumption that it's "really tough" to reach either temperature (400 or 500F) is wildly incorrect for the realities of cheap stovetops around the world. Gas / propane is widely used and can cause teflon to begin smoking within a minute or two.
But yes, it's probably fine on your fancy glass induction stovetop.
And by "ceramic" I assume you mean the faux-"ceramic-coated" ones that don't actually contain ceramic, right?