Obviously, you can serve pretty much any cereal which isn’t too high in sugar, but I would like to just make a special mention of raisin Mini-Wheats or Toppas. These do not contain any added sugar, and little ones can eat them by themselves with their hands – you just soak them in milk until they’re a bit squidgy. My ds will happily pick at a bowl of them next to his usual breakfast of toast or roll with jam.
Another big hit recently has been honey pops – puffed wheat with honey. I serve them in a bowl either dry or with a splash of milk. Ds eats them with his hands, or has attempted to go in with a spoon (better when they’re slightly sticky with the milk).