It uses USB-C for the charging cable. The cable between the headset and power supply is a locking proprietary connector, discussion on hackers news indicates it’s because USB-C locking connectors are not elegant and it has specific power requirements so using it with a random cable and random battery pack is not a good idea. The “battery pack” is also the power supply for the processor, it’s not really locking into a proprietary cable any more than it’s locking you into a proprietary operating system. Saying either of those is essentially meaningless to the discussion of the device.