If you have a rooted Android device or a jailbroken Kindle device, yes, you can still use Calibre DeDRM and KFX Input plugins on the kindle ebooks downloaded on them. It just takes a bit more setup with getting the key you need.

Unfortunately, DMCA takes an extreme stance when it comes to anti-circumvention. Even personal backup doesn’t have a strong legitimacy case under it, especially not when it comes to the tools that enable it.

Very related to this, LockpickRCM is a tool whose entire purpose is to extract your own Switch keys for the titles you own, and in turn is far more useful for people who want personal backups than those who are pirating the games. Still got a DMCA takedown two years ago, and though it never went to court it’s extremely unlikely any court would have ruled in their favor if it did.