I think I'll need time to settle my thoughts on it but it feels very much like a spiritual sequel to The VVitch in ways that The Lighthouse isn't.
From what I've read, one of Eggers's frustrations with the reaction to The Witch was that people tended to take its ending at face value. In The Lighthouse the most fantastical elements are far more heightened, and this is doubly true in The Northman. As a result I was less inclined to think of them as actually happening than more.
This is separate from any thoughts I have about the movie itself. I just think this approach is interesting.