I really like all of these ideas. It would be tricky to turn the Palpatine footage into holograms since he looks so different in TROS than in ROTJ, but maybe even filming a new actor in costume with an obscured face could be used to dub the dialogue over.

I agree that the ending with the Force lightning needs something else. I think it needs to connect with the fleet literally and Rey stops it, otherwise you run into that same issue of Rey’s journey being disconnected from saving the Resistance and the Galaxy. Plus, incidental falling debris knocking Ben into a pit would be similarly unsatisfying, I think.

It’s all worth pursuing though. I really like the idea of obscuring Palpatine’s face and dubbing him over with a very different voice; in my head I read your dialogue as sounding something like Vaneé from Rogue One.