Very well done, especially the first part.
On the second, my own approach would be to have Kylo again experience that vision, but cutting Vader’s head off coincided with his rejection of the dark side at “Endor” (😉).
I recently found the Kylo vs Vader fanfilm. I think one editor a while back borrowed something from this for a Force Awakens edit, but I think it could be integrated into Rise of Skywalker fairly easily and be used to inform the audience of a lot of Kylo’s motivations. You could also push his journey to Exogal up to follow from it
Here’s what I came up with (password: fanedit)
Beginning
Ending