Like its predecessor, The Beast 2.0 is being developed in secret because all of its various systems and defenses are matters of national security. We are fairly confident that it has lots of armor protection, glass that's about five inches thick, and special systems to clean the air in the event of a biological warfare attack. The current Beast is also said to carry a pint or two of the President's blood type just in case something does happen.
When the President is being transported in a motorcade, he is at his most vulnerable, so Cadillac One and the vehicles that surround it have to be prepared for almost anything. In fact, two identical presidential limos travel together to make it harder for would-be attackers to do bad stuff. The Suburban escort it's getting here at the GM proving grounds is appropriate, since most of the vehicles used by the Secret Service to accompany the President's motorcade are big GM SUVs.
By the looks of this camouflaged prototype, GM is nearing completion of testing the new Presidential car. The styling is a mix of CT6 sedan and Escalade, with a little XTS thrown in, and it looks a lot more sleek by comparison than the current blocky Beast. When it's ready, President Donald Trump will be the first to ride in it on official business and the current beasts will probably be retired and end up in a museum.