In my mind, Han showing up is simply the visual representation of Ben’s inner monologue - he’s not actually there. The scene is just for the purpose of filming something visually. “Leia channeling the Force into a medal that Han wore for 45 seconds one time 30 years ago, in order to project a conscious, sentient image of her dead husband to their son, who is halfway across the galaxy, several hours after her own death (because Finn and Poe have managed to fix the busted, crashed Falcon, leave Endor, and get all the way back to the Resistance before we see Kylo again)”…yeah, I don’t buy it.
If you wanted a visual metaphor for Han, why not use the dice? You know, the dice that were used throughout the previous movie to represent Han?