Chewies medal is explained because Leia is holding it as she dies in this edit. Therefore, it represents both Leia and Han for him (the medal belonged to Han originally)
As for the Reylo kiss, it makes things come full circle in the saga. Ben really did complete what his grandfather started: saving the one he loved from death. The kiss helps sell the idea that their relationship can be compared to Anakin and Padme’s.