Actually, feeding raw to a dog is not a bad thing at all. And it is the most ideal thing you could do for a cat (I only say this because I did little research for dogs specifically). I won’t hijack this thread and make it a debate about raw for dogs, but I did want to state that.
I would avoid leaves because a lot of fruit trees and oak trees are toxic in every single way. Even if there were trees around that you could confirm were safe, I would worry about them being mixed up, and then being unable to identify the safe ones from the toxic ones (as mentioned above), and ending up feeding completely toxic leaves to your poor bun.
I personally love the idea of a natural, fresh diet. But if there are a ton of risks involved that you might not even be able to avoid due to lack of knowledge, I would just scrap the idea. It sounds really good in theory, but there are a lot of potential problems. 