How do I stay full until lunch after having breakfast?

Protein and complex carbohydrates. I put protein powder in my overnight oats. Or avocado 🥑 toast. Health and allergies allowing.

It depends on the type of breakfast you eat. As in I mean that if you would prefer having a healthy, hot and short meal in the morning around 8:00 am, then you will probably feel better, full of energy and well nourished.