Funny that Darkstar is actually quite similar to the project name of another X plane: Blackstar.

The similarity between “Blackstar” and the “Dark Star” in “Top Gun: Maverick” could indeed be a nod to the history and mystique surrounding classified aerospace projects.

Blackstar is often compared to other rumored or declassified programs like the SR-71 Blackbird, the Aurora spy plane, and various DARPA projects. Its secretive nature and advanced capabilities place it within the realm of speculative black projects.

Lockheed Martin is working on a SR-72 concept plane

https://en.wikipedia.org/wiki/Lockheed_Martin_SR-72