If I had to guess…I'd do Frozen fruits. Put them in a blender for a smoothie, or honestly, I love to eat some Frozen fruits Frozen.
If you're doing a sandwich style breakfast that can be defrosted the night before. I've found overnight oats can be blended and frozen but they don't hold up as well compared to batch making them in advance.
look at the list of ingredients. Does it give you a source of protein to help you maintain the rest of your day? what about some fat? is it high in carbs? depending on what the rest of your day looks like, you will want to keep an eye on how much your intake is.
If I'm in a hurry I prefered frozen waffles, frozen fruits or scramble eggs with ham and cheese. This one comes in a bowl ready to microwave.
Frozen yoghurt, homemade frozen smoothies or frozen fruits such as mixed summer berries or forest fruits. Frozen fruit goes can be combined with normal yoghurt for a delicious breakfast.
If you mean what frozen breakfasts qualify as healthy, I'm sure not many. Maybe Kodiak frozen protein waffles? Or use frozen fruit to make a protein shake? I think the point is to eat whole foods. Maybe try meal prepping some hard boiled eggs or scrambled egg cups with zucchini and peppers. Those are some of my favorite quick breakfasts.
If you have time I like to make frozen breakfasts from scratch in batches, and eat it through the week, that way you have full control. Other than that, protein is a big plus.
I started buying the “just crack an egg” breakfasts which aren’t frozen but definitely aren’t “fresh” and then started meal prepping something similar on Sunday nights.
A low calorie low carbohydrates breakfast sandwich that is also low on sodium. Maybe a whole wheat muffin with scrambled eggs and veggies.