There is a fork of Readarr that works pretty well:

https://github.com/pennydreadful/bookshelf

I don’t see any ads in my Apple TV interface aside from some shown in the streaming apps themselves. We’ve been very happy with ours, keeping in mind the whole family already had iPhones.

That sounds like more trouble than it’s worth. You can get a SAS to SATA breakout cable for < $20 on Amazon.