I installed Moon+ and it seems to be working OK. I have only loaded one book so far. I vaguely recall having to jump through a couple of extra hoops, more than I do with my iPod, but I got it to work
I like the Moon+ reader on my tablet more than I like reading on my iPod. Bigger screen, and Moon+ has night mode: white type on a black background. My aging eyes like that better than black on white.
I haven't been able to afford a rubber case for the tablet yet, so I'm not taking it out of the house. Old iPod still useful as my purse reader. It's lighter as well.