That has to be either the Sorbet Kingdom or Elbaf
I hope instead of dedicating an arc each for Elbaf and Vegapunk, Oda lumps them together.
Like SHs reach Elbaf, solve whatever conflict is with Loki, get an info dump, and then mid-arc WG orders an SSG fleet led by Vegapunk to destroy the country. SHs rally the giants and they fend them off.
Didn't the giants destroy the gods in Norse mythology? It would fit well to see them destroy Seraphims "angels". Besides, Elbaf has the strongest army in the world, most fitting ally to fight the SSG/Marines.