It is not the easiest option, since you first have to root / unlock the device. (Which can be tricky, especially with the latest firmware.)
Actually looking back on it now, I should not have recommended this...
If you want to try Android on an ebook reader, the best option at the moment are the devices from Likebook or Onyx. They run an already opened Android version (6.0) and have much more powerfull hardware.
Take a look at the Likebook Mars or the Likebook Muses.