Tbh I'm surprised they're not making their own test. I was under the impression that NGAD is currently roughly near the 2001-2002 J-20 prototype stage. There should be enough material to show the public, and then from that point on, nationalistic coping will do the rest (in saving face).
It is funny that Americans cope by saying the NGAD is secret when it literally has to be shown off. The politicking behind it is incredible, not to mention the quite literally billions of dollars in the stock market that depend on this project. If Boeing doesn’t get it they might seriously be done.
Also, if the USAF really knew how to be humble they wouldn’t have bragged about B-21 the way that they did.