When I was a kid in grade school in the 70’s, in Western lower Michigan a friend’s dad had a local gun shop. He said a guy in the area bought some higher end military rifles etc there. He was a Vietnam vet and did mercenary work in Rhodesia and elsewhere that would hire him. The local paper did a fairly sympathetic article about him. He described his former military service and how he wanted to keep fighting communism wherever it was trying to take root.
https://en.m.wikipedia.org/wiki/Mitchell_WerBell_III
Werbell was OSS in WWII
My dad and I got invited to sight in our hunting rifles on his personal range (back in around 1973) a few times. You can read his bio. I got to listen to him tell quite a few stories, one in particular about a mission to dispatch Che Guevara.
In high school, I part time worked in his sons retail business, Brigade Quartermaster.
Solder of Fortune Magazine use to have advertisements for such people. I don’t know if that magazine still exists or not. If it or its equivalent does exist, it is probably a website and not in the English Language.