This looks quite nice. I always wished there was something like "Ruby Under a Microscope" for Python (and other languages). It was quite instrumental for my deeper understanding of the language.
That's nice too, but it seems to be more a tour of the code base, and doesn't have the detailled diagrams of memory layout that the Ruby book and the one posted here have.
https://realpython.com/products/cpython-internals-book/ But it's for 3.9 and doesn't cover the massive changes regarding delayed annotations and the GIL updates
The Ruby under a Microscope guy is updating it.