iPhone 15 Pro not working with USB C headsets (3rd party earbuds with mic, headsets, etc.)

I've tried several different USB C headphones, headsets, directly and with adapters, and nothing is recognizing the headset as an input/output device. If you make a phone call with a headset plugged in, the ringing still comes through the earpiece at the top of the glass.

Music works fine! However, voice memos and phone calls do not.

Is this a software limitation of iOS that might be fixed now that the iPhone is in the USB C universe? Or, hardware, where phone calls will only be supported by the USB C Apple Genuine Earbuds?