managed to get the Game Capture HD60’s video into OBS on macOS(!) via a local RTMP repeater (custom minimal build of nginx with the rtmp plugin)
delay is… a whole fucken lot, sadly https://awoo.space/media/jJ33bN1Kn5WD_7DfIQ0
the other side of this question: is there a way to add a delay to individual audio and video sources in OBS?