People that had similar ideas ended up bricking their Kindle in the process

@Marek (author of LanguageBreak jailbreak) bricked a PW4 trying to "retrofit" that Chromium browser.
And I think I read somewhere that 5.15.1?? firmware update has removed the diagnostics from PW3? So if that's true that would make unbricking PW3 without opening it and soldering wires to serial connection pads no longer possible?