I have at least two devices that are “USB-C” for charging but will only work with USB-A to USB-C cables. USB-C wall warts seem to need a handshake the device doesn’t do. So I still can’t throw out my old wall warts and cables. It’s terrible.
It can be done with 2 resistors. It's kinda required because of the same port on both ends. If I plug a battery into a phone, should the phone charge the battery or should the battery charge the phone?