ESP32 Forum

Does ESP-IDF has API that we can send buffer data to my hosts machine with USB interface?
For example, on ESP32 side, we would like to use its Wi-Fi connection to get an AP MAC address and use USB interface to send the binary data of the AP MAC address to my PC.

The ESP32 does not have native USB, what you're thinking of as USB most likely is the USB-to-serial converter connected to the ESP32s serial port. So the most likely API for this is the UART api, or just printf if you're feeling lazy.