I don’t think there is an easy way to DeDRM the latest kindle format used by the Mac/pc and iOS reader, and there is no easy way to download all kindle books in your account for “transfer to device via usb” for e-ink devices all at once. I’m trying to archive my 4k or so kindle books (already did a similar number of audible using openaudible) because I don’t trust Amazon to preserve access to them indefinitely.

You can however still download and use an older version of the kindle program (at least on windows), which download the files with the old DRM scheme.

It's one by one though.

Anecdotally, I've become aware that the Windows Kindle installer version 1.17 works fine for downloading your paid-for Kindle books and format-shifting them or making a personal back-up in a more open form. That information was current about a year or so ago; hopefully that version has not been hobbled since. Also, disable auto-updating.

I strongly suggest you only use it for your own purchases. Authors need to heat and eat too.

Kindle 1.26 works as of a week ago, if you also install the KFX Input in addition to dedrm. Best to look at the readme for such tools to get the latest info in any case.

You can find older Kindle versions for Mac as well without too much effort.

Didn't work very well on M1 mac with latest OS when I tried but I can probably run it on x86 somewhere.

I’m away from my M1 Mac at the moment so I’m not sure which older version of Kindle I ended up installing, but it worked fine to download my books, which was all I needed it to do.

I looked and I'm running 1.30.0. It wants to update every time I start it, but I just say no and it runs (slowly) but fine.

QEMU might be an answer. Not a sexy one, but DRM has never been a sexy issue.