Hi, you’re right, using mobile AR can be a better solution. No need for markers.
A PC webcam is bound to a cable or built in a monitor. A smart phone or tablet can take care of all tracking AND transmit the camera image wirelessly, that’s another plus.
Suggestion:
If you want to capture the image from the device, just make an AR project and look for a way to stream the content to a pc.
(it’s easy on ios devices, i am not very familiar with android)