There were plenty of restaurants and cafes open on that day. Many churches were open and available to visit. Giardino Giusti was also open. Casa di Giuletta was closed though.
Even though I have not been there, I would say the best thing in Verona is neither museums, shops nor restaurants, it is walking around in the city and enjoying the beautiful architecture. I am sure you can spend at least a day strolling around.
Credit:stackoverflow.com‘