I don’t know if you cats are aware, but Clone Trooper Captain Rex has been confirmed to have been part of the team that invaded Endor in Episode 6 “Return of the Jedi”.
The confirmation came from his appearance in “Star Wars Rebels”
We have not been given any word on what happened to the Clone Troopers after they were dismissed from the Empire.
Captain Rex was a First Generation Clone Trooper, I believe 4 or 5 generations were put in service before they were retired.
That will be a major cameo if Captain Rex and other well known Clone Troopers are still alive and partner up with Boba. That might be the Army Fennec might be talking about.