The walk from the ferry landing to the Hotel del is a fine walk. Coronado is a much safer and cleaner area than most of San Diego. There are some shops/restaurants that you will pass on the way, as well as some pretty houses.
There is a beach in front of Hotel Del that you can use and a little further from that is one of the more popular beaches including an off leash dog beach. I'm not sure what services will be open when you go. Things are slowly reopening and if Hotel Del has everything open again, you could easily get a full days worth of meals right there and keep yourself busy for the entire day.
There's also a Lowes resort close to Hotel Del. I think they sell day passes to use all their stuff. I have never been there, but I've read good things about it. It doesn't seem to have an actual beach, though, like Hotel Del has.