So Loki's Devil Fruit seems to be a Zoan one, more speciffically a Dragon Fruit.
It Also explains why Rocks thought that only by Harald eating the fruit would it reach it's full potential, cause this form is massive. the combination of natural strength and size paired with an enormous animal allowing for a monster with unparalleled size with all that comes with it.
This enormous dragon form of Loki is so huge that he can beat up and lift his father, a giant of the same size as Oars like he's a ragdoll.
But there is a bit more to this.
Firstly, this dragon-form isnt the kind of dragon that momo and Kaido have through their mythical devil fruits, nor another mythical variation, because just from what we see, this is an example of one of the one piece world's historical dragons, a now long since exctint monster.
this monster doesnt have the most impressive showing so far in the manga, serving mostly to be decapitated by strong swordsmen in a single blow, but they have, historically speaking, done something that makes them one of the most terrifying creatures in the OP universe.
They ended the first world by bathing it in a sea of flames.
No wonder Loki thought he was destined to usher in the end of days, with such an apokalyptic devil fruit at his command.
it also further ties into Loki's ambitions, and the norse themes and parallels of the arc, by tying it to the mythical Nidhogg, a dragon that tried to end the world by nawing at the roots of the world tree in an attempt to bring it down and end all life dependent upon it.
