I think it’s generally best to leave the Will of the Force open to interpretation, and the idea of ‘destiny’ as it pertains to Rey ambiguous as to whether it’s a destiny from Palpatine or the Force directly.

Back on Luke, perhaps we can have it both ways elegantly again:
“What are you most afraid of?”
“Myself…”
“Because you’re a Palpatine? Did you forget my own father was Darth Vader?” (said in an almost cheeky, lightly teasing tone)
-or-
“Because you’re a Palpatine? You’re talking to the son of Vader [right now].” (said with amusement)
“Final lesson. Rey… Some things are stronger than blood. Confronting fear is the destiny of a Jedi. Your destiny, if you don’t face Palpatine, will mean the end of the Jedi. And the war will be lost. There’s something my sister would want you to have.”

This way Luke’s still referencing his own explicit dark bloodline, with the link from Vader to Palpatine left to the viewer’s memory. And it’s still relevant - he’s showing the best person to advise on ‘my blood is scary’.