The Raspberry Pi Pico is quite interesting. For very cheap you can have a basic but powerful in and out microcontroller. It can be programmed with C++ or MicroPython. You could use something like Thonny to program it in MicroPython. It may be soon compatible with the Arduino IDE. Read more on this effort here – Welcome Raspberry Pi To The World Of Microcontrollers.
To create the Pico, Raspberry Pi created a new chip called the RP2040. It is a Dual Core Arm Cortex chip with 264kb of RAM.
The Raspberry Pi Pico comes with :
- 25 GPIO pins, 3 of which can be used as analogue inputs
- 2 × UARTs, 2 × SPI controllers, and 2 × I2C controllers
- 16 × PWM channels
Read more about Getting Started With The Raspberry Pi Pico.