Eli Vanto gets to see two of them without their armor when they go undercover.
They also appear in Season 1 of The Mandalorian. Rebels, however features them more prominently. Granted, this may be a reflection of how Hera's team of two Jedi padawans, a Mandalorian, and a Proud Warrior Race Guy were significantly more formidable combatants than Jyn's own Ragtag Bunch of Misfits. The elite soldiers of Imperial Intelligence, the Death Troopers are responsible for guarding key installations and personnel of the organization.
