Silly-Sausage missing 3.5mm headphone socket
There are USB-C adapters for headphones or dual ones for additional charging that might work. Bluetooth headphones should also be an option.
I think you made the right choice for watching porn. When I switched from Q2 to Q3, I wasn't overly excited at first. I had read a lot of forum posts about videos not looking better and screen door effects and I saw all that as well when I put it on for the first time but that changed from the 2nd or 3rd time I used it. When I go back to Q2 now, the overall experience is (subjectively) so much worse than Q3. And even if you are not into PT videos, I find being able to safely move around in a room with the headset on very convenient; the other day with Q2 I felt almost blind.