[mintplant]

All e-ink Kindles prior to firmware 5.8.8 can be jailbroken without hardware modifications.

https://www.mobileread.com/forums/showthread.php?t=275877

The Kindle hacking community believed they had a permanent solution prior to the release of the latest firmware version; unfortunately, Amazon seems to have finally found a way around it.

[bdelay]

I don't think anyone with experience hacking kindles believed it was a permanent solution. Unfortunately, most of the technical expertise in that area is fleeting.

I'd recommend an older Kindle if you want to get root easier. 5th generation Paperwhite and older models should be cheap and have various exploits.

Probably would recommend a Kobo or something else though. Kindles are awesome pieces of hardware but they do try to keep them secure. Not the best choice for an open platform.