Low sugar Meal replacement or protein packed smoothie. A liquid meal is better after fasting so it doesn’t shock your digestive system
Yogurt. Specifically plain and unpasteurized if possible. Get those microbes, you know? I mix it with two different types of fruit. And I throw some nuts or seeds on top.
Medium-boiled eggs and coffee. I cook a dozen in an egg cooker on the weekend, ready to eat during the week. More filling than cereal.