Overnight oats which you can prepare the night before. Soak some oats in milk and keep it in the fridge for at least 2 hours for the oats to soak up all the liquids. Toss in your favourite toppings, like freshly chopped fruits, or even some chocolate, and it's ready to eat.
I don't understand, even if the airline doesn't maintain any wheelchairs of their own, under special circumstances like these, can't they simply borrow one from airport services or something? Surely the airport has some wheelchairs around? Rather than have the situation end up in the utterly humiliating way in did.