We didn’t generally have school canteens like that in Germany, you bring your own food.
The few times my parents could force me to actually visit that wretched place, I don’t remember ever bringing food. I ate properly at home after school.
I remember my mother packing me sandwiches until maybe 4th grade.
I don’t need to eat anything in the morning, and generally not before 14:00. It actually makes me sick. I never eat breakfast except drinking a cup of hot chocolate (which is my equivalent to the morning coffee).