A few options I guess but I doubt some of them:
- Blackbeard makes the most sense since he had a ship scouting the day prior, buuuuut him "rescuing" a bunch of scientists seems out of character
- The SHF imo is possible but its been literally less than a day since the news of Luffy being at Egghead broke out, which makes little sense for the entire fleet to congregate
- Shanks even less so because he was going after Luffy's fleet and/or Blackbeard, so he'd have to follow suit with the above 2 choices, not be the first to arrive.
- The Revo's make even less sense, we just got Dragon/Iva scenes 2 chapters ago and they are still in Momoiro
- CG "can" make sense if their goal is capture Seraphim or something (idk what happened to the 3 chasing them), but imo they will go after Weevil, Moria and Doflamingo, so again, unlikely
- Germa would be odd but align with reuniting VP with them and payoff a cover story
Tldr: I really have no clue lol