You could probably grind some oats and corn meal, hard boiled egg and some greens each day. maybe 1/4 cup per chick. It probably won't keep long so you will have to offer it too them many times during the day. Your main concern is getting them enough protein to grow. They are making feathers that also takes a lot of protein. Farmers have been raising chicks for centuries without purchased feed. The purchase feed has many advantages and if you feel like you don't want to purchase food that is fine. Are they with their mother hen because she will have them trail her and they will eat most everything she eats or are you keeping them in a brooder? You will need a lot of grains and grit the fat content is important too. Of course you can raise them without purchased food and you probably won't mind the work. There is no rule that you need to purchase chick feed. Chickens are foragers and will find lots of things to eat, frogs, lizards, worms, berries....they search all day long.
I tried feeding mine organic chick feed - It came full of worms and then it molded within a week.
No preservatives.
Now I just buy it in the small bags. Purena Chick starter
That is my choice but I will respect your choice.
Caroline