Well, if you ferment grapes in the right way it makes wine. Fermented apples are a little different, but the outcome is kind of the same. Pickled cucumbers come to mind in regards to the process of repurposing fruits and vegetables.
Sorry I'm being vague about this, but it's all I know about it.
I often wondered if fermented apples made you drunk (like wine). I'm new to this too. I wouldn't have put pickled cucumbers (pickles) and fermented apples in the same category. I've got a lot to learn on this topic.
We actually make cinnamon fermented apples. They are a great probiotic and super healthy. We just started this a few years back. I watched something on YouTube about the super food. We tried them, loved them and have been eating them since.