It has to have a musical link to it. Banjo had to collect notes... So a music sheet has pages and we're talking about a Ukulele. So Pagies would be the equivalent of Jiggies. I'm really happy to see where this is going!
What if the pagies were actually printing paper and you needed to bring them to POOP so that he can print out maps or passes that open up new worlds. Or he teaches you new moves and you need to bring him the paper so he can print out the instructions.
Oh, and the librarian is evil because she wanted to be an author but her ideas were always criticized. So she decided to collect pages from all the books and create the ultimate story using other people's material. Plus, she'd leave the books ruined in the process thus destroying all competition. POOP used his printing technology to "print out" the protagonists from the tropical jungle book before their home was destroyed and bring them to life to save the other worlds.
I was gonna write up this whole big thing but I actually really like that music sheet idea too, considering music has been such a big part of the charm of the Banjo games and just Rarewares' games in general (also would be interesting to see music notes make a return, but that may be a little too similar to the past)
I thought Pagies implied book pages, not musical scores. The musical idea does sound pretty cool though. We cannot really speculate on just a name; we'll need to wait for a few more details to slip out...
I think the storybook is a good theory too after all B-K was meant to be a something like a parody of a classic child story.
Maybe the pagies as you guys said are part of a book and when you get more, the missing parts of the worlds will appear "expanding" it. Like you would miss adventure details if a page on a book was scrapped.
I think you guys are looking at Project Ukulele too literally. I don't think it has any connection to music; I think it's a joke on Banjo. The only thing I get from it is that it's an exotic Hawaiian-themed jungle, which is roughly what the screenshots we've seen look like.