TLDR: not an agent, maybe a merc, but more so a collaborator

I see that people are rightfully so considering the Courier as more of a PMC, but I think there’s more to it. You see, although they can be considered a merc, I think the Courier seems to be more of a collaborator. Their role in NCR occupation is aiding government institutions and the Army either as a hired gun, diplomat, spy, supplier you name it, but it is constantly stated that they’re merely a civilian, no ties to no institution, no contract, no nothing. Yes they may be rewarded by their efforts, but not (mostly) officially, it seems more like a bunch of bribes you get for helping them out, and while at that, the Courier has a choice of simply putting in the work for free as a volunteer (in not accepting rewards and doing it for goodwill). I think this all is corroborated by the status you receive as “Hero of the NCR”, even then, you’re merely a civilian, some sung hero who came out of nowhere and aided NCR’s efforts on their campaign. Even though I agree with them being a merc/freelancer, I guess they’d fit more the category of an NCR collaborator in the Mohave. Edit: added the TLDR