I want to be able to eat in Creative Mode. Is there any way to do this with commands?
No, there is no way to eat in creative mode in vanilla (unmodded) minecraft. The purpose of eating is to replenish your food bar, but you never need to do that in creative mode. That's also why you can't eat in survival with a full food bar: there's just no reason to. See: Why can't players on creative mode be able to eat?
The one exception to this are golden apples and enchanted golden apples, solely because they serve a purpose beyond just filling up your food bar.
Depends. In Bedrock Edition (Pe,Xbox,ect.) You can eat in creative and peaceful if you've gotten the most recent update.
Simple answer, there is no way at the moment. However, they might add one in the future