Serial might have been a bit unnecesary here, since there are USB hacks you can exploit to achieve the same over at mobileread.

You also might want to turn off some background scripts in /etc/init.rc/ such as the screensaver, unload the audio/mic, stop the window manager if you're not using it, and stop the webreader.

https://github.com/pascalw/kindle-dash/blob/main/src/dash.sh