Just found out about this new HMD from Pimax:
Looks like its the same hardware of the 4K, but stripped of screen and most of the electronics. The front where you put your phone, looks the same like the Homido HMD.
Maybe this might be my solution to get the headphones separately, since I bought the 4K without them, but I kinda want them now for the sake of convenience. If @PIMAX-Support could tell me if I have a cheaper option buying them from Pimax directly, I would do that instead.