For Kindle specific ripping, I think it changed a year back and now you need to have a kindle connected before the Amazon servers poop out some magic unlock key/the whole book. After that you’re golden, but during the rip you need a kindle device…
They explain the Kindle difference when using Calibre DeDRM tool in this article.
These are a bit more make your own story: Rimworld with Multiplayer mod (feels like its vanilla multiplayer tbh) and Project Zomboid :)