I've been looking to upgrade my old kindle, and saw this new feature called Immersion Reading that Kindle Oasis supports.
Basically you can seamlessly switch between an ebook and the same audiobook, but of course you have to own both.
I am wondering if people here have used this feature with a pirated ebook and audiobook.
If I uploaded them both to the device, would kindle recognize them and allow me to use immersion reading, or is it better protected?

Not sure about the answer to you question BUT I do use my iPad for my audiobooks and my audible recognizes the files as if I had downloaded them to the library. Maybe the Kindle would as well?