There is no real technical content in the link, just vague hints and repeated (see the book for more info) all over. The page doesn’t make it seem like it’s a description of the book - it makes it seem like “here’s how to build this” then doesn’t deliver.
That and the fact that the page starts off by talking about how it’s all open source and shared with the community was really incongruent. Flagged as spam.
I’m pretty sure that even Gmail spam detection system is better at detecting “spam”.
There are two links in this site to “backshed” forum detailing the circuit, pcb print, schematics and firmware. The main page is a showcase/summary.
The book is just a comprehensive guide/compilation, you can build without it. It’s mostly about wrapping the TF and best practices.