Buy your food in the deli section ready to eat, then rewrap it at home before your operation. Use that sticky press and seal wrap and/or ziplock bags with the pull-tab to store everything.
You can get a deli meat platter and precut veggies, cheese and fruit.
Sandwiches are easy too as long as the filling will stay put. Make some ahead of time.
Single serve boxed drinks are good.
Buy easy to open items like- cottage cheese, crackers and anything that you can cook in the toaster. A small waffle can be eaten by hand and dipped in syrup. Squeeze bottles with the lids off will be easy to use, look for the type with a flip lid- mustard, ketchup, syrup, jam, mayo all come this way now.
Tiny red potatoes cooked in the microwave can be eaten by hand and frozen fried chicken, meatballs, frozen dinners, meatloaf and stew or soup would be easy to eat.. Freeze whatever you can in single serve portions.
I think once you actually go up and down each aisle at the store you will find lots of stuff that you can manage.
You could also open some of the jars and cans beforehand and put the contents in ziplocks and store them in the frig or freezer.
Good luck Cats. I hope this helps you out and that the surgery goes well.