Oh no there are plenty of other examples involving federal agencies, but they’re far more rare. A big part of how the second amendment helps is that it prevents the government from even trying. It’s much harder to quietly disappear people in the middle of the night with secret police when the attempt would cause a loud and deadly shootout that would rile up the rest of the rabble nationwide. You’ll have noticed how even our currently blatantly corrupt government had to save face and fire top officials after just two people died in open confrontation with police. Dozens of armed standoffs nationwide would not be conducive to their plans.
The pentagon isn’t relevant, that’s a military institution.