what kind of table scraps can chickens and ducks absolutely not have?
Any thing you can eat, they can eat. Here are the exceptions. Avoid giving sweets, and things with (much) salt added. Also avoid things that might be a choking hazard.
I give my hens all vegetable leftovers, breads that are not fresh for my consumption, as well as meat scraps. I don't over do it. If I have a lot, then I spread it out over time.
Just use common sense as to how much is right.
WISHING YOU BEST and