This is definitely a direction I’d considered, but didn’t pursue because it is built on Prequel lore that isn’t explained in the prequels themselves. Also, according to that lore, wasn’t Anakin born as a direct response to Palpatine’s experiments in the Force? This is why Anakin is the chosen one, because he is the Force’s answer to correct the evil that is Palpatine.
For Rey to be another chosen one like Anakin would imply that she is meant to be another force of light to counteract the evil of the Sith, which goes against the idea that Rey is genetically or spiritually a Palpatine and thus is destined for evil.
To fix this, you seem to be changing the lore from Palpatine’s experiments creating an opposing reaction to counteract evil to Palpatine intentionally creating vessels for his dark spirit as a way to gain immortality.
So if I understand this correctly, Palpatine created Anakin so that he could inhabit his body after Anakin destroyed him, and this was only thwarted on Mustafar. Then he tried again with Luke, and again it failed. After that, he decided to create a new vessel with Rey, since at the time the only surviving Skywalkers were out of his reach and control.
It could definitely work. It would also feed into Kylo’s motivations, and perhaps most of his explanation to Rey in their fight could concern his family history and what Palpatine was trying to accomplish with it. He could say that all of the Skywalkers are drawn to the darkness by their nature as beings created by Palpatine as his spiritual heirs, and Rey is just his attempt to perfect this process as you say.
This would also give Leia a good reason to abandon her Jedi training, and it comes at a point in the story where such an explanation makes a lot of sense.
“Because you’re a Palpatine.”
“Leia sensed your darkness as well.”
“Leia was quick to learn in her training. However, she feared the darkness that had lived inside my father, and still lived within me. She surrendered her saber to me and said that one day it would be picked up again…by someone with the strength to finish her journey.”