An alternative to Rey needing to be a Palpatine to have conflict, could be her struggles with the Dark. Force lightning, her relatively high power, it could all be because she leans towards it.
I saw a great interview with Dave Filoni (I think it was part of the BTS for Mandalorian) where he talks about why the fight between Obi-Wan, Qui-Gon and Darth Maul is the ‘Duel of the Fates’ - it’s the duel for the fate of Anakin’s soul. He expands, that Qui-Gon is the first Jedi to realise the failing of the light side, and the issue with the Jedi serving a corruptible republic. He explains that, had Qui-Gon survived, that HE would have been the one to train Anakin, and would have raised Anakin to learn to manage and accept his darker side, rather than treat it as a binary thing to reject (at first) then allow to consume him (like Vader).
And remember, we have that through-line of Qui-Gon being the first one to be able to exist as a force ghost, passing it on to Yoda and Obi-Wan - the two other most enlightened jedi. So right from the beginning (well, the PT), it was intended that balance beat light or dark.
And I believe that the balance concept of Lucas’ scripts remained part of the intention in the ST. In the first Jedi temple, there’s the black/white buddha statue. Luke himself says “at the height of their power the Jedi failed to stop Palpatine” and that “it’s time for the Jedi to end”.
I think that leaves us with a solid through-line of Rey being the inheritor of that line of thought, from Qui-gon to Yoda to Obi-wan to Luke to deathbed-Vader to Rey, as the idea that balance is the way into force-heaven. Green lightsabers seem to be a signifier that they’re on this path.
And that conflict with the dark which becomes acceptance and balance doesn’t need to include a relationship with Palpatine, if it can be played up - while still being a satisfying conclusion to the entire saga.
(And in that context, Rey declaring herself “Nobody” works as she’s accepted who she is, just as declaring herself “Skywalker” implies “the inheritor to that line of enlightened thought”. Her creation of a gold lightsaber would signify her being the one to ‘conclude’/‘refine’ it, leading the next generation in balance.)