We don't really have a natural analog that has existed for millions of years, off the top of my head.

Some contact metamorphic rocks might be similar in crystallography and chemistry, especially shales intruded by basaltic magma. Hornfels is a really hard and dense c-metamorphic rock. The general term of similar rocks, "skarn", was supposedly a word derived from a curse made by Scandinavian miners.

Chert lasts for a very long time. Some of the oldest rocks on earth are cherts. They are similar to ceramics, sort of.

So, yes, I think those spark plugs, insulators, and grandma's fine china plates will last a long time.

However, unlike those thick banded iron formations of the earliest deposits, the thick skarns, there is simply not enough ceramics in the world to make anything more than odd fragments in a schmear of odd sediments on an enormous bagel.

We know about dinosaurs because they existed for a very long time. Humans not so much. There is a vast record of dinos in the geologic column long before the K-T event. Our creation of ceramics (I include pottery here) goes back what, a few tens of thousands?

I would be interesting to take a representative sample of the average landfill and subject it to the temperatures, pressures, and aqueous chemistry that is diagenesis and lithification of sedimentary rocks. Why not kick it up to various metamorphic facies, while we are at it? A landfill's components brought to high grade metamorphic P/T conditions?

There are ways of doing this experimentally right now. But the samples are typically small. And we cannot recreate millions of years in a lab.

If we want to use ceramic clasts in a humanite in a Science Fiction story, we need to trace the entire geologic history of that deposit.