Are there any 3V I2C chips that are actually confirmed to be unable to handle this very tiny current through their ESD protection diodes?
I don't understand the question. Why would you be connecting a 3.3V device to a 5V processor without some kind of level shifter?
So far, no one knows about a chip that got damaged.
Because one of the advantages of I2C being open-drain is that, you can just use a pull-up resistor to 3.3V instead of 5V, thus you don't need the level shifter