Raspberry Pi Pico
All you need to get started on your own projects are a few low-cost Picos plus some prototyping boards and jumper wires.
Unless you are happy to use a soldering iron choosing a Pico with pre-built headers is a good idea.
If your project is based on the Pico W, an original Pico can be used as the debugging probe and now you will find Pico Debugging probes commercially available.
You also find a logic analyzer handy and to build the projects outlined in the book some specific sensors, servos and motors. Luckily all of these items are readily available from Amazon.com and if you make a purchase via these links you won't pay any extra and we'll get a few cents.
Just click on the product pictures or text links to go direct to the product.
Raspberry Pi Pico W
DVOZVO 4Pack Raspberry Pi Pico W with Pre-Soldered Headers
Vilros Raspberry Pi Pico W Project Starter Kit
Raspberry Pi Pico RP2040
available as single, 2-pack or 3-pack
C4Labs Zebra Pico W Case
available as single or 3-pack