I had an original Onyx Boox and it was so terrible, inflexible, and softwarily out-of-date from the moment of shipping that I gave it away within about a month. It was also slower at even responding to page-flip commands on PDFs than my iPad 2. And I'm giving it a fairly wide berth for the slower refresh rate of e-ink-- talking push button 3 seconds elapse blanks and draws new page

edit: I see that they're still shipping Android 6-based devices in 2020. Lovely stuff.

It's way too big and expensive for the purpose. And all the smaller one don't do it. I would consider a 10" screen for sure but 13.3"? That's too much.