Dude, comparing USB headphone consumption to 3.5mm jack headphone power consumption is laughable. The power consumption is so negligible it’s insane. It’s on the order of magnitude if you were to forget to turn off the light in a room for 1 minute each year. Phones themselves consume extremely little power, I forget the exact number but I think it’s in the realm of a few kW/h per year, and USB headphones are going to be a fraction of a percent of that