How does Kylo get to Exegol in this scenario? The theatrical is already relying on the audience not minding that, at some point between movies, Kylo figured out that Palpatine is on Exegol, and that the only way to get there is with a wayfinder, and that Vader had a wayfinder on Mustafar. It would be weird to move this scene to the middle of the movie (he somehow finds out where the wayfinder is, goes to Mustafar and grabs it, zooms over to Exegol, makes a deal with Palpatine, and still gets to the Death Star at the same time Rey does?), but it would also be a bit odd if he found it at the beginning and then just didn’t use it.

You also might need a bit more… something, to sell the urgency and legitimacy of the Resistance’s quest and Rey’s inner conflict. If we haven’t seen Palpatine in the flesh yet, the first mention of him in the movie will be Poe’s “somehow, he returned,” which now becomes even more laughable. The audience would be thinking, “What? They’re risking everything because they heard some guy say Palpatine has ‘returned?’ They know Palpatine was in the Death Star when it blew up, right?”