The Krypton season 2 finale teased the arrival of the Omega Men, a cosmic superhero team from DC Comics. The inclusion of an "Omega" symbol was one of several DC Comics connections found in the episode. However, it's doubtful any of these storylines teased in the finale will ever be addressed.
Just two days after the finale aired, it was reported that Krypton had been cancelled after two seasons. The cancellation of the Superman prequel series likely came about as a result of low ratings and high production costs. Furthermore, DC has decided not to move forward with Lobo, the Krypton spinoff that was confirmed to be in development at the start of Krypton season 2.
In what will now be considered Krypton's series finale, Nyssa-Vex (Wallis Day) takes Adam Strange's Zeta-Beam device and teleports to Rann on a mission to find Sardath, believing that he can help her find Jor-El. Right before seeing a group of winged men flying above, Nyssa notices an "Omega" symbol painted in red on a rock wall. No explanation for the symbol is given, but the primary conclusion to be drawn is that the Superman prequel series was getting ready to introduce the Omega Men in season 3.
In DC Comics, the Omega Men are a team of alien superheroes based in the Vega solar system. Introduced in 1981 in Green Lantern #141, the Omega Men consist of super-powered warriors from various planets. The Omega Men act as peacekeepers of their sector, often teaming up with other cosmic heroes like the Green Lantern and Adam Strange. Since Green Lantern Corps aren't allowed to patrol the Vega system, protecting it falls to the Omega Men. The Omega Men spend most of their time fighting the Citadel, the oppressive and fascist empire who controls the vast majority of the worlds in their sector. Over the years, there have been several iterations of the Omega Men, but most incarnations of the team count Tigorr, Primus, Kalista, and Broot among their most important members.
Krypton introducing the Omega Men makes sense, considering that, during season 1, Krypton star Cameron Cuffe confirmed in a tweet that the Omega Men exist in Krypton's universe. DC Vice President Dan Evans has also suggested the possibility of the Omega Men appearing at some point.
The Omega Men are only one of many teases featured in the finale. The episode also sets up Hawkman, the Rann-Thanagar War, and Superman's Yellow Sun powers being used as a major plot point. The sheer scope of it all suggests that Krypton season 3 would have greatly expanded Syfy's corner of DC Universe, which is another reason why the show's cancellation is such a disappointment.