The Mandalorian's season 2 finale featured a scene with a ruthless Imperial who said he'd survived the first Death Star - but how did he avoid being killed when Luke Skywalker destroyed it? Before Luke's destruction, the Empire was undoubtedly a force for evil in the galaxy, but, oddly enough, they went a little too far when they destroyed Alderaan. The Galactic Core had previously been able to pretend ignorance as to the Empire's true nature, but now one of their own worlds had been destroyed. Grand Moff Tarkin's strategy of fear backfired, with Alderaan's fate leading millions to rebel.
Things might have been different had the Death Star remained operational because the threat of absolute destruction would have terrified anyone who thought to rebel. But, as revealed in Rogue One: A Star Wars Story, the Death Star had actually been sabotaged, with scientist and head architect Galen Erso deliberately ensuring the reactor was dangerously unstable. All it took was one well-placed shot to cause the space station to explode - and Luke Skywalker was the one to make the shot, aided by the power of the Force. It seems impossible that anyone on board might have survived - and yet, for all that is the case, The Mandalorian's season 2 finale featured an Imperial officer who claimed to have survived.
Curiously enough, there is actually precedent for Death Star survivors in Star Wars canon. Claudia Gray's novel Lost Stars features two such survivors, Thane Kyrell and Ciena Ree, both of whom watched Alderaan's destruction. Leia's lie to Tarkin that the Rebels were based on Dantooine saved Thane's life because he was a member of the scouting party sent from the Death Star to check it out. Meanwhile, Cienna Ree was assigned to the Imperial Star Destroyer Devastator, the ship that captured the Tantive IV over Tatooine, and that briefly docked with the Death Star in order to transfer Princess Leia; it remained in the Alderaan system when the Death Star headed to Yavin IV, although it remained linked to the station's data feeds right up to the moment it was destroyed.
Lost Stars confirms Darth Vader was the only Imperial to survive the destruction of the Death Star; ironically, his life was saved by Han Solo, whose shots had sent Vader's TIE Fighter spinning away from the Death Star. This meant Vader was far enough away for the explosion to not affect him; once the Dark Lord of the Sith regained control of his craft, he skillfully piloted his vessel through the debris field until he was picked up by Imperials.
The Imperial in The Mandalorian season 2, episode 8 was most likely the pilot of the scouting ship sent to Dantooine. He claimed to have been assigned to the Death Star, after all, and spoke with the vicious bitterness of a man who had lost friends and colleagues when the Death Star was destroyed and thus had only doubled down in his hatred for the "enemy." There is a certain irony in the fact he was ultimately killed by an Alderaanian.