And then Galeem proceeds to take over Hinawa's mind and force her to attack Lucas :(

Do you think other spirits and characters reuniting would be equally as sad?

Mario meets Pauline or Luma
Link meets Marin, the four Champions or Saria.
Toon Link meets Medli.
Snake meets The Boss
Shulk meets Fiora or Reyn.
Ness meets his father or Paula.
Corrin meets Azura.
Chrom meets Lissa.
Isabelle meets Digby

And the one that hits me hardest in the feels:

Bayonetta meets Cereza.