I did a WGU CS degree, which had a lot of online testing.

It was honestly fine. They made me use an HD webcam, show my drivers license, and pan around the room to ensure I was by myself and didn’t have an easy way to cheat. They also made me share my screen on Zoom and open up the Application Monitor to ensure I was only running Firefox. They didn’t let you take notes on paper, just using a portable whiteboard that they watched me erase before leaving.

I’m not saying it’s impossible to cheat, but I would say it’s probably roughly as difficult as cheating in person. Presumably the SAT stuff would be comparable.