we’re still in wano act 4 trust
No, we're in Wano Act 3.5, we can tell because Yamato is still chowing down
Imu IS telling Shamrock that Teach is heading to Wano, though, after Caribou told Teach, Kuzan heard, and spilled the beans to the WG/Marines.
I think Elbaph's first part will last like 30-35 chapters.
We're 20 chapters in, and Shamrock can return easily. Luffy's chapter is 56: Shanks is in Heaven World, which is why Loki knows where he is. Luffy and Shanks should reunite in 1156; that makes me think this is actually the final fight of the first half of the arc.
Once Shamrock comes back, he'll tell the God's Knights they have to go to Wano, to fight Teach over Pluton.
Yamato's Cover Series will lead directly into Wano Act 4
Expect a big explosion at the end of Yamato's Cover Series.
IMO I think Jack is going to fish the bombs out of Onigashima from underwater, and they're going to use them to excavate the area Kaido and Linlin are trapped in.