I'm not sure what you mean by "filler," but a lot of chicken foods are based on corn and soy, with other things added until it's right nutritionally. The corn is not "filler," because it is providing calories, part of the protein, and certain vitamins & minerals.
Any feed described as "pelleted" or "crumbles" should have the ingredients ground up and mixed together, then shaped into whatever form. Because everything is ground & mixed together, the chickens cannot pick through and eat some parts while skipping others.
I would try whatever is in your local feed store, and see how it works, before searching for things that might be more expensive or difficult to get. The important thing is whether your chickens eat it willingly and do well on it.
Maybe I should explain my concern. I had a duck many years ago that was either laying a soft rubbery egg or egg bound. It was sooo awful.

I don’t want this to happen to y sweet hens. I want to make sure they have the best I can get for them.