Another random idea!
While the movie in general felt rather rushed, I feel like the opening scene was even more rushed than the rest of the film. We got one planet shot, then it jumps IMMEDIATELY to the ground, which has never happened in a saga film, since a ship usually transitions the audience naturally from space to land. We get a few shots of Kylo Ren fighting random people, then he opens the chest and immediately transitions to him flying to Exogol. Before we even have time to know where we’re at we’re already gone. I didn’t even know that planet was Mustafar until I read about it later. I originally wanted to cut this opening and start straight with him flying to Exogol, but I had another idea.
What if we created an opening scene that mirrors the opening of The Phantom Menace? Instead of the Trade Federation invading Naboo, the First Order invades Mustafar.
No new footage would have to be shot, but some visual effects could be used to create some new shots.
Opening crawl, tilt down to Kylo Ren’s TIE Fighter flying toward camera, then pan left following as it passes camera (like Republic ship in TPM). Mustafar enters frame, where a dozen Star Destroyers orbit the planet. TIE fighters and troop transports invade planet surface. Montage of Kylo killing Vader cultists. Kylo then arrives at Vader’s castle. Paralleling Queen Amidala watching the invasion of Naboo from the palace window, Kylo stares out the castle window as TIE Fighters fly by and Star Destroyers float above. He then enters another room and finds a stone chest, pushing the lid off to reveal Vader’s Sith Wayfinder.
Reusing some footage from Rogue One (and hopefully some deleted scenes and additional visual effects), you probably could make something like this work and allow the opening of the film to have time to breathe.