The Arduino Nano itself is the most basic and oldest of the group, and just like its many iterations, it's designed to work primarily with breadboards, making it a great tool for prototyping.

The Raspberry Pi Pico is both faster and cheaper than the Arduino Nano, but the nano has better resources and community.

Arduino Maker Nano RP2040 “Slightly shorter than a Pico, this board has 30 pre-soldered pins, all helpfully labelled on the silkscreen.