Raxter54

There are no webCams on any of the PC's onboard that I have encountered.  I also used my IPhone using VOOM (Slower if you use basic VOOM instead of surf & Stream but still works). You can then use the Shipboard PC and printer to access your email to print a copy of the results if you are like me and want a hard copy in case you cannot get the original email to display when asked to show your results on the phone. It has happened to me at the airport in Copenhagen when I was unable to access their wifi and thus unable to show them proof of a negative result. 

A test from the cruise ship would suffice but they will charge you if you aren't sailing again with the cruise line. 

Welcome to the boards!
I'm not sure the cafe computers have cameras. Perhaps someone currently/recently on Allure can comment. Otherwise people have been reporting success in using Voom to test.

My son used his cell phone in Europe.  It is easier than a laptop to adjust distance for the images the proctor will need.   I don't remember from Mariner whether the computers have cameras.  My son tested when the ship was closer to disembarkation port to get best connection.

Maybe it's been discussed before, my apologies if so...would the medical staff on board be eligible/authorized to be your proctor?