I personally don’t agree with the idea of “revealing” Palpatine’s survival earlier to the audience. Yes, I do like the idea of seeding the possibility of his survival, whether it be through Rey or Kylo, in visions they see or voices they hear. It should be all but confirmed before the last film, where, in an alternate universe, we would be having fans speculate on why Kylo is hearing Palpatine’s voice, or who that hooded figure was that Rey saw in the dark side cave, or who she heard/saw in a vision. So it is almost a given that Palpatine will show up in IX, in some form. It is a thin line to walk, but I think you have to find that balance for it to feel satisfying, and not shoehorned.

You could even blend Snoke and Palpatine’s voices occasionally, like in TLJ, when Snoke says, “Give, me, everything.” You could take Palpatine’s “everything” from IX, and blend them together. Just enough to get the audience to scratch their heads, you know? Especially since the Emperor’s theme plays during that exact moment.

That may have been what you meant, though! I just personally don’t like the idea of putting any of Palpatine’s scenes into TLJ, for example. But to each their own.