most of the information is pretty concise and well maintained.
start here
https://www.mobileread.com/forums/sh...d.php?t=320564
if you get a kindle oasis 3 then currently no jail break exists. get an older one with a firmware that can be jail broke and then you are in business.
after jailbreak is installed, it can persist through firmware upgrades but the important thing is get it jailbroken.