It is, though, I've just done it a few days back. Once you have a clean text extracted from the book (this is actually the difficult part, removing headers, footers, footnote references, etc.), you can feed it into edge-tts (I recommend the Ava voice) and you get something that is, in my opinion, better than most human performers. Not perfect, but humans aren't either (I'm currently listening to a book performed by a human who pronounces GNU like G-N-U).