Kludge DRM removal, at least for macOS users:
https://github.com/mcandre/tigris
Inspirated by Comixology Backup.
Food for thought:
* A Kindle for PC (Windows) would want to replace AppleScript with some combination of PowerShell / .NET
* BlueStacks + adb would provide a cross-platform solution that works regardless of the host OS (think macOS, Windows, Linux, BSD, ...)