Through all this, keep in mind that chick starter is formulated to be nutritionally complete for birds of that age based on over 100 years of research. It is hard to beat that with treats. The data is in, we know what vitamins, minerals, protein, fats and energy is needed by poultry at all ages for optimal growth.
Chickens can live, grow and likely prosper with so-so nutrition but to get the utmost out of them, optimal nutrition is important to provide from hatch on.
Chicks, being small and growing rapidly, should have every bite they eat be fortified with all the elements necessary for body development and immunity. This is especially true of essential amino acids.