This might not be a very pirate thing to do but I cancelled my Kindle Unlimited when I found out I could get all of them, for free, delivered to my Kindle app, from my city’s library via Libby. Books, graphic novels, audiobooks, manga, and more, just there for the taking.

I don’t remember the steps, but there used to be a way to do it through Calibre. You could download your library into the Kindle desktop program, run a DRM removal tool, and have them available through Calibre.

You might have had to remove the DRM through Calibre, I’m not sure. Hopefully this gives you somewhere to start though :)