As an owner of a PW2 you are in danger of being hit with an update to firmware 5.6.1
Currently, firmware version 5.6.1 would place a serious limitation on your choices.
To help you decide what you want to do first, See:
https://www.mobileread.com/forums/sho...81&postcount=6
None of the i.MX6 Kindles (2013 and 2014 PW2, 2014 KT2, 2014 KV) are a good choice to practice/learn on.
We can't 'auto-debrick' those.
Instead, get yourself a used K4 or K5 to start out on.
Those can be 'auto-debricked' with Kubrick.
The K5 was the last model with audio device support -
It uses the IR scanner touch screen, like the new KT2 does -
There is a lot of information here about the K5, both in the forum and in the Wiki.
On the other hand -
The K4 is approximately 'throw-away cheap' by now.