Although the Rebel Alliance had its own secret version of Exegol, they actually wasted it in the Star Wars galaxy. As revealed in the animated Star Wars Rebels series, the individual Rebel cells that would become the Alliance discovered a world that was similarly remote and hard to access, making it the perfect planet to hide from the Empire and build their forces just like Palpatine did with the Final Order on Exegol. However, it seems this hidden world was left largely unused by the Rebellion.
In The Rise of Skywalker, Kylo Ren locates a Sith wayfinder, an ancient artifact that safely guides him through the dangers of the Unknown Regions to Exegol, the hidden Sith world where Palpatine resurrected himself and built a brand-new fleet of Star Destroyers and soldiers for his Final Order. Known as a "box system," Exegol had strategic value as there was only one way in or out. As such, the same concept proved to be true in Star Wars Rebels with Lira San, the secret homeworld of the Ghost crew's Zeb Orrelios.
