This only supports Arduino 1.0, not the newer 1.5 versions, but now [Dave] has a great little prototyping board that can be put together from perfboard and bare components in a few hours.

For instance, the ATMega328P code is written in Arduino-supplied C++, but ESP32 and RP2040 in particular used MicroPython, which does more than just running the code, and MicroPython for ESP32 in ...