"Microcontroller programming" – synonyms could be embedded coding, firmware development, or hardware programming. Not sure if "programming" is okay. Maybe embedded systems programming, firmware coding, microcontroller coding?

"Customizability" → "Adjustability|Customization|Tailorability". Maybe use "Customization|Tailoring|Adaptability".

Original text: "Type Away with ESP8266: Building a Bluetooth Keyboard"

"Design and build" → "Configure and Construct|Create and Assemble|Design and Make".

void setup() // Initialize the Bluetooth module BluetoothSerial.begin(deviceName, pin);

Step 3: Setup Bluetooth