I sort of wish the surviving rocky planets from Jupiter’s grand tack were in the Planet X arc.
For example, Ganymede and Europa could still meet Planet X except now at his hideout there’s the survivors hanging out with one another. It wouldn’t exactly be possible because in the big bang arc we see that Planet X doesn’t think “what if they survived and are just past the Kuiper belt, in the Oort cloud, etc so I doubt he searched around or used his abilities to see and hear from very far away. Still, it would’ve been very interesting to see the group studying the solar system and coming up with plans.