The bootloader, however, occupies 2 KB of the flash memory, so you essentially have 30 KB of usable space left for your sketches. The Raspberry Pi Pico is fitted with the Raspberry Pi-made RP2040 ...

The Arduino Nano uses a bootloader for handling programming the MCU, which requires the USB to serial bridge to be disconnected from anything that could interfere with the programming.

The Nano ESP32 supports both Micropython and Arduino programming languages, providing a clear path for those already familiar with one platform to easily switch back and forth as needed.

The board is built around an ATtiny3217 and has almost all of the Nano’s features, like a USB port, reset button, built-in LEDs, 5 V regulator, and preloaded bootloader.