Orson gets 1/2 kibble and 1/2 cooked. His kibble is grain free, but HE is not grain free.....I control the quality/quantity of grain he eats.
His cooked food includes organ meat as well as muscle. Long grain brown rice or oatmeal. Various RAW blended veggies (blended to aid in digestion/absorption), I make it a point to include broccoli and sweet potatoes. Broccoli has calcium and vitamins, sweet potatoes are a digestion favorite....they help cut down on stinky farts IMO, LOL And both of those veggies are shown to have good cancer fighting agents as of current studies.
Orson normally gets a few raw meaty bones from the butcher each week, and he also gets a dollop of yogurt on his breakfast each morning. And of course his cookies/treats............simple sliced/dehydrated sweet potatoes are a favorite in addition to his homemade peanut butter biscuits.
You could absolutely include egg shells. It's easy to do if you remember to save them, LOL Microwave them to dry a bit, not long. Then blend them to crumbs and add them to your dog food.
IDK, I don't go nuts trying to keep everything perfectly balanced. If I have a certain question, I'll look it up. Otherwise, I look to Orson for answers. He is healthy, his poop is good, his skin and coat are great, eyes clear, energy level great, teeth great, and so on. If there's a problem, I'm sure his poop and coat will be the first to tell me, LOL