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.

So you've already outgrown Arduino's most beginner-friendly board, the Uno, and are looking to move on to bigger, more exciting projects. In that case, the Nano family might just be what you need ...