I'm just copying my suggestions from the other thread, and I'm tagging
@Margarettt who was interested in this thread as well.
I have no experience with hospitals thankfully, but lots of experience packing for a week of sailing without a fridge, and with very limited options to cook.
I am pretty ok with snack foods, plenty of ideas there. it’s more the meals, breakfast and dinner,
Snack foods are food too, and they can make a nice meal as well, just a little different from 'normal' meals.
You already have a low carb roll with salmon, cream cheese and cucumber as part of your evening meal, with coleslaw regularly. Swap the salmon for cheese or so (do not keep salmon outside a fridge!), and like
@Annb said, coleslaw will keep for at least two days outside the fridge, and you'll have a meal just like at home.
There are lots of foods usually kept in the fridge which will keep well unrefrigerated for 4 days. Yoghurt; cheese; hard boiled eggs; salami or other dried sausages; my favourite midnight snack of chicory leaves and hummus or pork scratchings dipped in aioli; avocado; tomatoes; celery stalks and peanut butter (yuck!); cucumber (just throw away the dried out end slice before use), and then there are all those foods that don't need refrigerating anyway: nuts; high % cocoa chocolate; cheese crisps; low carb bread, you can even take the toppings from the hospital bread to put on your own, just bring some butter and marmite.
All the best with your operation!