I had a theory that the "Unidentified flying object" calling card was a hint for the Gong relic (Another one had a hint for Nikolai side EE) because it showed a character killing a zombie while not hitting the other 4
So since there was 4 zombies and a 4 star constellation lined up in the sky I had a thought that maybe you need to kill only 4 zombies with one shot from the LGM
Sadly it didn't work but it was fun relic hunting