I think anyone should be able to say Nigga or Nigger if it's in reference to the word or in a novel/historical text (and that they should do so) or in music, which has been my perspective ever since reading half of Huckleberry Finn in elementary school.
Beyond that though?
Don't use it in conversation/as an insult, and when it comes to nigga, take that up with the black people up in your immediate vicinity.
Where i'm from there wasn't really ever any policing of it so despite being black that discussion wasn't very relevant until High School which was when all of the police shootings/protests were breaking out and myself and other black kids started developing our social justice ideologies and started to make shifts in what we accepted in our friends circles/from others and what not.
I'm ambivelant on it in either direction mostly, but it's probably just easier not to say it and if you say it to not say it within the vicinity of any black person who hasn't "cleared" you to use it (not that I believe in the concept of a "nigga pass") and not to say it if any black person tells you not to.
Especially since so many people who try to fight to say nigga end up being bigots themselves or people who don't care about/dismiss the black fight for civil rights/the issues that plague us as unnecessary and fiction, not cool.