In terms of powerscaling for the giants I always assume that we just haven't met the giant equivalents of guys like Kuri, Doffy, Vergo, Sanji, Zoro, Luffy etc. yet.
Within the human high tiers (Burgess, Oven, Jack..) and even within the human top tiers (BM, BB..) are also guys that are not really that agile mobile, super skilled and "aware".
The lack of all that just goes extra hard on giants, especially when they fight overpowered humans.
"Thin and muscular" sounds already good, night mean that Loki at base is more on the fast af boi side instead of falling victim to the giant's effect.
Giants are also not excluded from having adv haki types and CoC, especially when they are royality and have a strong bloodline.
Oda can make him a fast and a profound CoO user and a gigantic CoA hardened Axe would already make him borderline top tier. The legendary DF would then do the rest.
It's not that difficult tbh.