As we know that there is a giant strawhat which belong to imu, we can depict it is from a giant. 



The only place where giant live is elbaf, so if you consider that joyboy was a giant and lives in elbaf it is a pretty good assumption that he lives in elbaf

We will also assume that joyboy rebelled against WG, well I don't think it's confirmed (please correct if wrong)but it is a pretty famous theory, so we will go with it

So now we know that
1) joyboy is a giant and lives in elbaf


2) we also know joyboy rebelled against WG 

 

 

The one last reason I think elbaf is laugh tale is because oda said one piece is in its last saga so its a good way to cover both elbaf and laugh tale at the same time 




 

The down vote is lin lin or big mom was left at elabf, but there are many theories which say that laugh tale is place where straw hats have already been, so it's not a bad assumption to think that a villain has been to laugh tale 

 

The last thing is about the poneglyph roger and his crew were reading, (if you read it this far then thanks but now its going to pure speculation no proof.)

 

 

The reason I can think about the where the poneglyh is:
1) it was another island not laugh tale, 2 laugh tale you wanna assume
2) the poneglyph was on elbaf but on a secret place and that were reading, how they knew about that secret place, its because of the poneglyh, it points to elbaf but no one talks about how it points to a place inside laugh tale.

 

For example, when the lines of poneglyh intersect they intersect at cordinate ((3,2) cordinate geometry)
Now imagine elbaf's (boundaries of elbaf or the four corners of elbaf)are cordinate
1st corner- (5,0)
2nd corner-(0,5)
3rd corner-(0,0)
4th corner-(5,5)
So people will thing its elbaf as the intersection of poneglyh lies in elbaf but the real treasure might lie not on elbaf but the cordinate where it points so the poneglyh is on (3,2), the cordinate pointed by poneglyhs .

 

 


And why do i support this idea because you don't know what poneglyhs actually say, so they might even tell about how deep it is or if its in sky because then we have a reason why the giants haven't founded the depth it is in, they might have stepped over it if its in ground or walked under it if its at sky