I really live Nev’s most recent take on things, it’s the cleanest marriage of Rey Palpatine & Rey Nobody. Rey’s uniqueness wasn’t because she was born/made/conceived differently, she was inoculated. I also don’t have an issue with Palpatine choosing a scavenger over a Sith loyalist for a few reasons. The main reason is that foolhardy Force users in Star Wars put way too much stock into visions and sabotage themselves as a result.

The second reason requires some explanation. There’s an old DC comic called Armageddon 2001 that depicts a fascistic society where conformity is enforced & heroism is outlawed (being a vigilante, memorabilia, etc.). The dictator of this society, Monarch, wants to conduct time travel experiments to both protect himself from unexpected attacks and ensure that his form of peace will last after he’s gone. The only problem is that none of his subjects survive the experiments, and the protagonist, Matt Rider, explains that it’s a matter of willpower: by outlawing heroism and enforcing draconian rule, Monarch is eliminating the qualities in his society that are necessary for it’s survival. As a result, Matt becomes one of the subjects for the time travel experiments and actually survives the process.

I can see Palpatine doing the same thing, looking for an outsider like Anakin that would have the necessary qualities that his followers wouldn’t have and setting up the steps necessary for Rey to one day become his most viable host. Also, like I said before, putting too much stake in his own visions and trying to get the outcome he wants. After all, his overconfidence is his weakness.

JEDIT: If you do need an even stronger reason for Palpatine to target Rey specifically, you could always make Ochi’s knife a Sith Artifact her parents found, of which Child Rey would be very succeptible to it’s influence and put a big target on her back. Still keep in with that “right place, right time” angle.