Here's the thing ... Breakfast can be anything from leftovers to Scramble Eggs & toast. There are things you can make ahead of time and freeze or go to a grocery store and pick something up. Most of the time I prefer not to buy food but to make it. I have a limited income so must make everything count.
One of my favourite breakfast foods is egg muffins, like a quiche but smaller they are easy to make and you can add meat & vegetables to them if you want to.
Best of all they are fully freezable so though you make a dozen you don't need to eat them all in a couple of days.