I personally use Gemsy for my non-fiction books, and it works amazingly. Especially their unique feature called Verified Print Copy Reviews, which allows me to receive reviews on paperbacks that include a photo or video. This is super helpful for algorithms!

Gemsy also offers a Goodreads reviews, which some people find helpful for extra social proof. I don’t remember the exact number, but as far as I know, after about 20–25 Goodreads reviews, the Goodreads rating starts to display on the book’s Amazon page.

Overall, it’s been a great experience. If I ever have any issues, their support responds pretty quickly—usually within a few hours.