Thank you so much for the very helpful answers re car rental insurance. It’s surprising how hard it was to find this info, and as always the forum collective knowledge comes in to save the day.

will look into it should AVIS insist damage happened during my rental period. I took pics and video before driving the car but not of that specific area where they later found the chip when I returned it, my bad. Though in general pick up was very rushed and unprofessional, with several other chips and marks on the car that were not documented in the contract. When I brought it up they said “just take the pics”. This was outside US so hopefully no need to involve my own insurance