> That said, the CIA stuff is presumably fake, given the huge amount of fake personas curated in LinkedIn over the decades for all kinds of nefarious purposes.

Plenty of people have open employment with the CIA. They likely need to get specific approval to post that on LinkedIn, but I guarantee many of them are real.

Source: Previously held TS/SCI clearance at an intelligence contractor. (I don't recommend cleared work, though, and I've been out of that world for years, thank God.)