I second the smoothy - I make my the ones for my kids with strawberry banana chobani greek yogurt, and then some frozen fruit. They love it and it's so healthy and filling.
Also, yesterday I put a hot dog from the fridge in the microwave for 30 seconds and stuck it in a bun. cut up apples on the side. Super fast and they ate, which is sometimes the top priority!
Bagels can work in those situations as well for us.
microwaved chicken nuggets (the morningstar soy ones we like and microwave well, or their chicken patties)
frozen meatballs heated up with jarred sauce, ideally with some fridge pasta