Once a book is published, you can access the read-only version online.
When you're reading a book, one of the sharing options you have is the ability to embed the book on a website. NOTE: this doesn't give you a full page-turning experience on your website. This will provide a snippet with a link, and the cover image, like the example below.
If you want to embed a book, click on the option in the menu and you'll get a full embed code. Click Copy to clipboard and then paste the embed code into a HTML editor. See the example below.
Here's the whole process: