Arduino coding.
Experience with inputs (potentiometers, keyboards, buttons, switches, rotary encoders), screens (oled, lcd, eInk, 8 digit displays), sensors (PIR, distance, humidity, light) and others (RFID, Relays, Vumeters, motors, motor drivers, IR temperature, mp3 shields, Mozzi library)
Machine Learning with TinyML and Arduino BLE 33.
Several Arduino book collaborations and popular projects.