They are confirming that, yes, it is an option to have a partition dedicated to just the user’s (your) home environment and folders
and
asking if that is an option that appeals to you or you have already considered.
It is what I prefer, but there are people who have good reason to not like that. It’s worth trying out imo, and later if you find that it doesn’t suit you, that’s okay, you’ll just need to find another solution
You’re getting tripped up with the words. It could be rephrased to “copying the data.”
The owner doesn’t have any way to access this copied information, but they do have the copy that is on their phone.
The reason the owner isn’t given access to the data is obvious. Because anyone with a brain would immediately delete it, but the car company wants to be able to use it