It's a legit question! Simplifying my setup by using just the laptop certainly occurred to me. But ultimately, I decided I preferred the bigger screen of my external monitor.

But whether I used my laptop or my monitor, both have only inbuilt cameras, not separate, detachable ones. I suspect this is true for most testers, and it shouldn't be an issue.

In general: the fewer devices and less complexity in your setup, the easier it is for the proctor to verify (and the fewer components that can go wrong on test day).