Arduino has shrunk the UNO R4 with the Arduino Nano R4 board equipped with the same 48 MHz Renesas RA4M1 32-bit Arm ...

The Nano is also a great choice when your code is pretty large. Since it has more usable flash memory than the Micro (30 KB vs 28 KB), it's better at handling long sketches.

Both the Arduino Nano and Uno can be powered via their integrated USB connectors. This automatically supplies regulated 5V power to the board, allowing you to use any USB-supported power source ...