need someone who's willing to donate an old Arduino board, and actually pull out the test equipment, and just actually what extremes starting with pin current,
The only way to assess damage is to slice the chip and look at the wiring and substrate with an electron microscope. That is what the manufacturers do when an important high volume customer has a problem. This almost always shows damage to the relevant part of the circuit. They then either reduce the recommended operating conditions or do something to the design. The latter is very very rare.
There will always be a bit of margin they add and a tolerance from device to device so pushing beyond what the data sheet says is possible, but it dosn't make it any the less a very stupid moronic thing to do.