Use them to make stock, they have heaps of collagen. My local market has them very cheap along with some hearts thrown in the package. I toss everything in the soup pot just like they were bones,. Toss in garlic powder, onion powder, salt, pepper & couple of Tablespoons of ACV, If I have them a stick of celery and part of an onion, whatever herbs strikes my fancy that day. Bring to a boil and then simmer for 2-4 hrs. Use as you would bone stock. The gizzards will be nice and tender and ready to eat, no flours of any kind required.
But in all fairness I should tell you instead of stock making you can dip them in a beaten egg, then into coconut or almond flour, both work well, and fry them up. They have always been my favorite part of the chicken.