You can display RTMP streams in OBS. I don't have an iPhone, but once helped a friend get a GoPro working with OBS this way using its wireless streaming. Just p

You can display RTMP streams in OBS. I don't have an iPhone, but once helped a friend get a GoPro working with OBS this way using its wireless streaming. Just plugging it in didn't work, it wouldn't just be a USB webcam. So, anything that'll let you stream with RTMP will probably work, and then you just have to input the URL on the OBS side.