You're technically right, and I appreciate your comment, but it's funny to me to be like 'It is headless! It just needs a fake head!'

Now you try working with a fake in your head's place! :þ But yeah, real head (a monitor; doesn't have to be on) also works just as well, and even no head at all works, just won't accelerate 3D. Arbitrary resolutions also work. My only complaint with sunshine is that the webui authentication is really broken. Fortunately I don't need to go there much.