The plausibly healthful cold cereals in supermarkets I shop now are down to shredded wheat, the original Cheerios, and FiberOne (expensive). The protein thing is a sideshow; the requirement for protein is only 70 grams/day, so most Americans are way over-proteined, and the milk (non-fat, of course) on your cereal is going to give a decent amount. Put fresh berries on the cereal as often as possible, other fresh fruit in moderation otherwise.