E (xxxx) i2c.master: I2C transaction unexpected NACK detected I²C scanners detect no devices at 0x3C or 0x3D, even though the OLED should use one of these. The OLED module has a 472 resistor (≈4.7kΩ), ...

MediaPipe is used to detect hand landmarks in real-time. Custom logic maps different gestures (open hand, closed fist, etc.) to LED numbers. Connect LEDs to Arduino digital pins (D9–D13 in this case).