There was a storyline in the pre-shoot version of the film about the Sith fleet, according the the leaker who later proved to be 100% accurate. Apparently, Generals Hux and Pryde were tasked with rounding up children in large numbers to train and staff Palpatine’s armada. Later on Kojimi, we would have seen Palpatine’s orders carried out as children weree being rounded up by soldiers of the First Order.

It’s a shame it got cut for two reasons:

You need hundreds of thousands of people to crew the fleet we see on screen. I was asking myself in the theatre: who mans these ships? The fleet’s existence can be easily explained away (Palpatine hid it away during the height of the Empire, they are all Imperial era Star Destroyers, not First Order ones).
The control tower subplot now makes sense. If the Sith fleet is manned, why exactly cannot they leave Exegol? I never understood that. But if these ships are uncrewed, you would actually need some kind of remote device to manouvre them.

Let’s hope for some pre-reshoot deleted scenes…