One symbol in USB-sysmodule is: "vtable for nn::usb::detail::UsbComplexTegra21x".
usb:ds
Not used by any sysmodule.
usb:hs
General USB devices usage, used by hid-sysmodule and bsdsockets-sysmodule.
usb:pd
usb:pd:c
USB-sysmodule symbols for this refer to "Cradle", which is the Dock.
usb:pm
Presumably Power Management, only sysmodule using this is PTM.