To be able to charge at the same time, you will need active headphones instead of passive which means an extra soundcard that will pull energy from the battery. As passive headphones when detected changes the USB + and - to connect the headphones to the internal soundcard/DSP-board and if you also insert 5v at the same time would probably fry the DSP-chip.
I'm using a USB active splitter and an old 3.5mm headphone so I can charge at the same time, it works but I do get worse sound quality and also lower sound levels this way. Best solution is a good bluetooth 5 headset, then you both get good sound and can charge the phone.
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