The Sith Apprentice from Exegol

Have you ever thought what if there where sith on Exegol before Lord Palpatine? And if so how did they live and what are their stories or the story of their apprentice?
Well this story is focused on one the sith Lords apprentice. Darth Phantom, he was a force sensitive boy that was born on the world called Trelex, and the law said any force sensitive kid was to be put to death immediately do no uprising would start.