I would like to give Palpatine his own scene in ROTJ, have him talking to one of his loyalists. Telling the loyalist to meet him on Exegol.
Take the scene where Palpatine is sitting looking out of the death star. Get a palpatine impressionist to say the line. Deepfake Palpatines mouth and we’re golden.
Also, Record someone dressed up as a Palaptine loyalist for the scene.
Since TROS came out my headcanon is that when Palpatine turns to his advisors after Vader leaves, he sends them to Exegol and that’s why they don’t appear again in the film. Therefore tying the Imperial advisors to the Sith loyalists, an idea firmly rooted in the wider canon.