That’s a good point about Rey’s point of view. Thinking about it, it’s not impossible to combine that idea with the Mustafar vision idea. How about:
Kylo kills the cultists and comes to a stop. Before him is the stone container inserted via VFX (cut the shot of him turning). He opens the box and places his hand on the square item inside. Use shot of him turning and then his environment dissolves into the interior of the cultist’s base on Exegol. After the Exegol scene it returns to the shot of Kylo standing over the box, this time with it open and the Wayfinder still upside-down inside.
This allows for the audience to put the pieces together as Rey does.
I like this idea but would you still use the Kylo traveling to Exegol sequence?