I rented a car in Catania last year and was also worried about all these insurance issues. The Car Rental Catania service, which is conveniently located on one website — https://findycar.com/car-rental-catania/ — helped me a lot. There you can immediately compare all the options, from cheap small cars to large family cars, and filter offers by pickup location — directly at the airport or in the city. I also paid attention to the fuel policy and the size of the deposit, because some companies block quite substantial amounts. It is convenient that the website shows these conditions in advance, so there will be no unpleasant surprises when you arrive at your destination. I also recommend taking photos of the car when you pick it up and return it to protect yourself from unfounded claims.