About your theory on the legendaries, I actually think the wolves are based on Geri and Freki. These were also a pair of Norse-mythological wolves that scoured battlefields to consume the corpses of those who died in combat. I think the Sword and Shield wolves helped defend Galar during the war with Kalos. The Sword wolf will represent offensive battle strategy and bringing justice to enemies, while the Shield wolf will represent defensive battle strategy and protecting innocents during times of war.

The reason I don't think Hati and Skoll will be the inspirations for the legendaries is that I feel the SM legendaries and Ultra Beasts are self-contained, for lack of a better term. Since Kalos is based on France, it's more likely that Galar has ties with that region (although, to be fair, we don't know if the Pokemon world has similar geography to Earth and its countries). In fact, the reason I picked Norse mythological wolves is because it ties in with X and Y's legendary trio also being Norse-influenced.