Not so long ago I decided I wanted to learn some C++ and ended up getting some cheap micro controllers and starting with Arduinos and learning from the examples in various libraries.

Now I'm having a lot of fun, still learning, while programming the ESP8266 and especially the ESP32 (via PlatformIO). Playing with Wifi and Bluetooth too.

The best thing in my view about learning things with micro controllers is the 'tangible' result. Seeing things happen or move. (or not! and why.)

I thoroughly recommend it, along with all the other responses here.