Elbaf won't take more than 20 chapters imo. It will be a set-up arc just like Zou. And I don't get the downplay against the Giants. People said they're mostly fodders which is not true. Back in pre-timeskip, Dorry and Broggy have their own mini version of Hakai which cuts the ocean in a long distance. Hajrudin is young but he's still pretty strong. Being the captain of New Giant Warrior Pirates and all. And even Big Mom said that if she had Giants on her side, she would beat Shanks, Kaido and even Whitebeard long ago. And she would have become Pirate King. So the Giants of Elbaf can't be underestimated.
Vivi having Kuma's fruit sounds weird to be honest. It doesn't fit her fighting style imo. But Koala definitely would be op with Kuma's fruit. Imagine Fishman Karate + Paw Paw fruit?