Those seem to be microstates, or small countries with the single dominant city along other cities, rather than city-states.

I'm aware they are listed in Wikipedia as "can be considered" city-states, but I don't think that's in the sense we mean here.

This matters because my main objection is that city-states in the same sense as Sparta, Athens, etc, no longer exist in the modern world, and as such, the question "is there a example of a modern city state being conquered?" is moot.