Well my mind does think of Hal (and others’) had about Rey’s lightning being yellow to help differentiate her use of it from Palpatine. And how the lightning she’s deflecting back at Palpatine could turn yellow, showing that she can embrace her anger without letting it control her. Basically, accepting her shadow-self without being afraid of it. And then that can help tie her yellow lightsaber to her newfound self-awareness.
But that kind of just doubles down on “Rey actively kills Palpatine” doesn’t it? I like the idea of Rey accepting her emotions but I don’t really like the idea of Rey being a good guy who is cool enough to use dark side powers too.