Star Wars TV shows tend to focus on filling in gaps in the canon rather than exploring anything that occurred after the events of The Rise of Skywalker. This leaves room to explore stories hinted at in previous entries to the saga, as shown in Obi-Wan Kenobi or Andor. Often, such as in The Mandalorian, they provide information about cultures that have existed in Star Wars for a while but have not been fully explored. However, one major group has yet to get their time in the spotlight: the mysterious Nightsisters.
Source:https://www.cbr.com/the-nightsisters-star-wars-future-projects/