I'm not trying to convince you that you're wrong with what I'm about to say. I (half) joked to myself that if this series finale didn't explain everything that they'd have to do an End of Evangelion for everything to make sense. After watching the finale I don't think this series needs this, at all, because the finale delivered on the real theme of the show. The show's true theme was always about this character's deteriorating mental health. This was always about Dissociative Identity Disorder. It wasn't about the hack, or Whiterose's machine, or the three missing days. At least that's how I interpreted the scene with Krista within the context of the entire series.