Using Bluetooth on a desktop computer is now such a seamless process; it’s something built-in and just works. Behind that ubiquity is a protocol layer called HCI, or Host Controller Interface… ...

The PCB holds an ESP32-PICO-D4 which is operating as a standard Bluetooth HID controller for maximum compatibility with modern systems.

Reports of undocumented Bluetooth HCI commands from ESP32 chips are doing the rounds. They open up a security flaw.