Its like I said before in my last post, I think the reason that Carrot isn't getting much of a focus in Wano, is because she got her time in Whole Cake Island. Despite this, Im willing to lay my hat unto a guess that Luffy already considers her a member of his crew, even though the story itself isn't really hinting much to it, or shoving it in our faces full blown, unlike Yamato.
Like, disagree or agree, not everything has to be made super obvious and in your face in who the new nakama may be, if there is one. Luffy, as such, is more likely to go and pull a Usopp in which Luffy just simply tells Carrot to come on board at the end of the Wano Country arc because they are already nakama. That or Carrot asks to join at the end and he's fine with it, just like how Robin just casually asked and Luffy allowed it with no issues. Sometimes, being simple works, just as Carrot, at her core is also a pretty simple character, both in personality and design.
Luffy is that simple minded, unlike us in the fanbase, where we look at every single point and tend to overanalyze everything about a single character, plot or ongoing arc as to prove something that may be not there at all.
As such, I myself am not expecting any BIG flashbacks for Carrot or a tragic backstory anymore during this arc, as all those things, as little as they have been, have been done during Whole Cake Island. No need to do it again. The least I can still reasonable expect, is that something happens between Perospero and Carrot that triggers a meaningful scene for her and ups her chances for joining. But for the rest, what you normally expect of a new Nakama, has already been completed, even if we, the fanbase may not agree with it and we want to see more.
All in all, where people try to find big meaningful stuff about Carrot that would supposedly heighten her chances for joining, Carrot itself isn't this complex character, but rather a SIMPLE one in every aspect about her. So if she were to join, its also going to be a simple thing, not something grandiose.