The Mandalorian season 2, episode 5 name-dropped Grand Admiral Thrawn, raising an intriguing question; is Moff Gideon the real leader of the Empire, or does he in fact report to Thrawn? The Mandalorian season 2 is subtly rewriting the history of the galaxy between the original trilogy and the sequels. It has revealed the war with the Empire never truly ended because although the Empire officially surrendered, there are holdouts far from the Galactic Core.
In truth, this was subtly teased in The Mandalorian season 1, because Moff Gideon appeared to be far more than just a warlord; he clearly considered himself a leader in the Empire. Meanwhile, there were hints the Empire had been active around Tatooine, with the locals putting out Stormtrooper helmets as a warning to any other Imperials what fate would await them if they should try to occupy Mos Eisley. This has been confirmed in season 2, with the New Republic investigating reports of Imperial activity in the sector around Tatooine, and Moff Gideon apparently commanding a fleet. But The Mandalorian season 2, episode 5 saw Ahsoka name-drop another major Imperial, Grand Admiral Thrawn. This naturally raises a curious question; who is the real leader of this Imperial Remnant, Moff Gideon or Thrawn?
In order to properly assess this, you first need to understand exactly how the Imperial government worked. Even a fascist government like the Empire technically differentiates between the political and the military branches. The Moffs were essentially governors of individual sectors, responsible for managing everyday life and enforcing the Emperor's laws. There were 20 Moffs when the Empire was at its height, and they reported to the Imperial Ruling Council, which consisted of Palpatine's closest allies and advisers. Interestingly, Moff Gideon appears to be an unusual figure in that he served in the Imperial Security Bureau, a law enforcement and intelligence agency that was usually separate from the political wing and that did not report to the Moffs. This suggests he may have assumed the title of Moff after the fall of the Empire and the Battle of Jakku, rather than being assigned it in the normal manner.
Thrawn, however, is a "Grand Admiral." This was a senior rank in the Imperial military, with Grand Admirals typically given command of an entire fleet. Thrawn is a particularly interesting case in point, because he was promoted to this position due to his strategic and tactical genius, but was actually completely ignorant of political concerns. This seems to have led him to depend on local leaders - including Moffs and planetary governors - in order to manage day-to-day administrative issues. But Star Wars Rebels strongly implied Thrawn was quite able to impose his will upon worlds and potentially even systems, should he feel the need to do so. The Empire, ultimately, venerated military force above political will.
Ahsoka Tano clearly believes Grand Admiral Thrawn is overseeing a buildup of Imperial resources in a number of systems. Meanwhile, The Mandalorian season 2, episode 3 confirmed Moff Gideon is responsible for the shipment of armaments and resources to supply a fleet of some kind. It's important to note that Moff Gideon is not based on an Imperial Star Destroyer, but rather on an Imperial Light Cruiser; while this may simply indicate the weakening of the Empire, it more likely suggests he does not have the military authority to command a Star Destroyer. Thus it is likely we are seeing a partnership; Moff Gideon in charge of the politics, Grand Admiral Thrawn as the supreme strategic authority. But Moff Gideon should be under no illusions that he can be any more than the Vader to Thrawn's Emperor, the lesser authority who serves a purpose and will be discarded should he cease to be of use. The interesting question, of course, is whether or not they are both reporting to Palpatine himself, who has been reborn on Exegol and is, of course, building up an army in the Unknown Regions. It's possible The Mandalorian's hero, Din Djarin, is unwittingly meddling in matters of supreme galactic importance.