Pets perpetually need help. And since they only have 2 gear slots, but there is not a single possible way to get any set bonus, as no collars are parts of sets, and no converted handwraps can be part of any 2-piece set with just an armor.

But there's armors that are part of a 2-piece set for all 5 (the Heroic + 4 Legendary) Feywild sets.

Make the Feywild Heroic collar part of the Heroic set, and the Feywild Legendary collar part of all 4 Legendary sets.

Being on a collar, this will have no impact on player characters, only pets, and, even with 4 sets on it, you can still only get a single 2-piece set bonus, from whichever armor you use.