Quote Originally Posted by Buried Alien View Post
In previous canon, Force ghosts were established as a Light Side-only ability (and even then, only Light Siders with the requisite knowledge), just as Force Lightning was supposedly a Dark Side-only ability. We saw Yoda call down Force Lightning in THE LAST JEDI, however, so perhaps all the old rules are out the window.

Buried Alien (The Fastest Post Alive!)
I’m not saying the Sith can learn to force ghost, just that they could do something similar to it. If anybody in Star Wars would know of a way to exist beyond death, I’d buy that the Emperor would have found a way to do so.