Though sadly the new types of Kinds require a method of extracting Kindles to PDF which is an order of magnitude harder than the old Calibre DeDRM method. I had to boot Bluestacks and export license files and rub my tummy and pat my head and do the Hokey Pokey… but in the end, the books are now 100% mine.

Edit: It’s been a while. Looks like the process is more streamlined, but still not what it used to be.