Additional Fields for Buy Button

I would like to be able to allow users to add additional content during the Stripe payment process because I am working with food items. For example, if you order a hamburger on my site and do not want ketchup on the burger there is no way to advise the vendor of this instruction. I can see how this can affect those selling products with different attributes (size, color, etc). We have an option for address but that is it.