If you only have a few pet chickens and you neighbours don't have any other chickens, then it should not be a problem feeding non medicated feed. I don't like to use chemicals or medications unless its really needed, I like my bird to build up their own strong immune system and not become dependant on meds.
I have never used medicated food or vaccinated any on my chicks. I have never lost a bird to disease or illness. In my area we even have lots of neighbours chickens roaming around and mixing with my flock. The only issue I had was scaly leg - which I cured with oil easily.
I think the medicated food and other stuff is essential for people keeping large commercial flocks, as disease can spread quickly in these situations and it costs a lot of time and money to sort out the problem.
Hope you chicks are doing OK......enjoy them!