I just remembered that there's a pretty sizable list of serpents that are said to be chewing on the world tree with Nidhoggr. Like Goin and Moin and Grabak and such. What if these were some of the main followers of Nidhoggr in your lore? Also, I really need to find a good source on those guys, because right now I just know them as a list of names.
I mean, that’s probably all the information we have on them - most of Norse mythology’s stories were destroyed by Christian invaders. But yeah all those guys would be prominent Root Chewers.