Check the firmware version.

https://wiki.mobileread.com/wiki/Prefix_Index
Above is a fair amount of documentation.

https://www.epubor.com/how-to-jailbreak-kindle-paperwhite.html
Jailbreak instructions for Paperwhites.

Probably no, as its firmware auto-updates and they closed the jailbreak a year or two ago. But who knows, put it in airplane mode and check it.

My 4th gen doesnt need it. I've got two D01100 models. I can literally plug them into my phone and copy paste books onto them. I google the book i want, download to my phone and just paste it into my kindke.

Just don't attach an account to it and keep it on airplane mode. They can't stop anything. I've even got manga on it but that took a converter program on my laptop to make the manga into an epub file.

That's what I'm looking into, too. I'm finding info about a Branch Delay, a WinterBreak, and a LanguageBreak. I don't know which one to try.

https://kindlemodding.org/jailbreaking/WinterBreak/

Jailbreak now available for all kindles