We do frozen waffle sandwiches- pb and j, pb and honey, honey and cinnamon, nutella, anything they like! Also mini sweet peppers cut in half and stuffed with hummus and feta has been a hit (not traditional, but it's healthy and filling).

We rotate between pancakes and Cheerios. She always has a handful of pistachios and fruit with it. Occasionally we make muffins and she might have one of those with fruit and nuts.

For protein:

Turkey sausage
Lox
Cream Cheese
Hard Cheese
Nuts/Seeds on something or by themselves

Or just leftovers or protein-infused pancakes and such as others have mentioned.

Mine survived on cheese sticks and strawberries cuties or blueberries , and occasionally pepperoni slices until they were 8.

French toast if you don't add much sugar is pretty healthy. Whole grain waffles with almond butter. Maybe egg "cupcakes"? Little egg bites.

Kodiak cakes (love how you can just make as many as you need) - one of my kids eats this every day
Whole wheat english muffin with peanut butter
French toast (make ahead and freeze)
Granola and yogurt

Whole grain blueberry waffles (we don't do syrup)

My kids don't like eggs be eat french toast so that is how I slip in the egg/protein.

Baked oatmeal is a hit here.

One of mine eats dinner leftovers and the other one whole grain waffles with fruit.

My DD eats dinner leftovers for breakfast every day. She doesn't like any breakfast food except pancakes.

Oatmeal pancakes? Fruit? Sandwiches or wraps? Sushi? It doesn’t have to be breakfast food. What foods do the like for other meals?

I add cut up fruit to whatever they’re eating. And cheese if I want them to get some additional protein in.

French toast
Kodiak pancakes
Carrot muffins

My kids are very picky: don't like oatmeal, don't like eggs, don't like yogurt or smoothies.

What can I give them for a healthy breakfast? Right now we've been doing plain Cheerios w/ milk and peanut butter toast but I need some more ideas of things that are reasonably healthy and will fill them up too so they're not asking for 2nd, 3rd. 4th breakfasts every day.

Thanks