Right. It stops at the point it becomes useful. They covered the basic theory of EE, and then got stuck. The project has apparently been stuck there since 2020.

"The Art of Electronics", by Horowitz and Hill, is far more useful. It's not an easy book, but it teaches you how to actually design and build stuff. The original target audience was physics grad students who need to build some piece of hardware for their research. Their explanations of how to think about what transistors do are very useful. Horowitz and Hill get across some basic useful concepts, such as:

* Components are not ideal, but today, many of them, operated within their limits, are pretty close to ideal. So, if you're not doing something that requires very high speed or very high power or very low noise, you can often use off the shelf parts in a straightforward way, without getting too clever. Arduino is this concept taken to the max.

* Learn to read data sheets. That tells you what you can buy and what problems you can get pre-solved.

* Design and build well-behaved sub-assemblies and connect them up. Don't try to do the whole thing at once.

* Learn to design PC boards. It's not that hard, and the tools are quite good.