As a start the navigator.mediaDevices.getUserMedia() works on iOS browsers. and Desktop browsers for video stream capture from users cameras.
See https://developer.mozilla.org/en-US/docs/Web/API/MediaDevices/getUserMedia for more details. on usage and support.
I have tested it on my iPhone with Mobile Safari and Chrome and once I allow permission it works.
The Same with desktops.
Note. The Hype Preview server in most cases should work for testing on Desktop (Chrome, Safari,FF) but not on iOS.
iOS needs the page severed from the https:// protocol.
Working simple example
video_Camera_Browser_Stream.hype.zip (9.6 KB)
Live demo