In most classified arenas, there is no private sector competition. No one in SV is building subs, SOSUS arrays or stealth a/c. So it's completely reasonable the

In most classified arenas, there is no private sector competition. No one in SV is building subs, SOSUS arrays or stealth a/c. So it's completely reasonable they're way ahead of some niche innovator building a sub out of carbon fiber. But it's not sci-fi tech. People talk about the SR-71 as an example, but the A-12 predecessor was only a secret for about 18 months. The P&W jewels were out by ~1978 or so. LM, afaik, doesn't do propulsion so there's no place to hide an anti-grav unit.