Ya

There really should be a third choice, since you could think one is canon and one is not. Both things shouldn't have been lumped together.

I thought about a third, but I didn't know what to say

Dagor Dagorath Is and apocalypse and should be viewed like the version in christianity, that said I would call it cannon yes as it is mentioned when Finrod has a conversation with Barahir (I think).

The new shadow I would not call cannon as it was unfinished and doesn’t really link to any other texts.

^i can’t remember if it was Barahir or Turin or Hurin…