I hope they don't have individual modules for individual islands. If so, collecting all of those will be both pricy and a pain.

Or lead to some real life piracy

YAAAARRRRRRR!!!

If they did it right then piracy is the only way to get them, no official channels...

Maybe it's done that way to encourage making your own stuff, while still being compatible with modules that you buy. Also, we don't really know how much they take for each module for this campaign setting, maybe they are cheaper for this reason.

I think you have module with several islands in them. None of them being mandatory to play. With major locations and plot-relevant (for the non-homebrewed plot) locations being included in the core material.
Bascically the modules are stuff you can purchase if you want more island.

I think you have module with several islands in them. None of them being mandatory to play. With major locations and plot-relevant (for the non-homebrewed plot) locations being included in the core material.
Bascically the modules are stuff you can purchase if you want more island.

I think its more likely that each arc of the series would be a module on its own

I've heard this anime is pretty famous for its extended filler arcs, maybe the filler arcs are the Official Modules, and the Canon stuff (heh, pun intended) is GM's own stuff that he's created for their game?

Maybe the order of the islands changes each time you play through. That way, there is no this module leads to this one, it's here's the tiers of modules, and you just play in increasing tiers.

If we go by real life supplements it’s probably less each island gets a supplement and more each route gets a supplement and if you have more then one you can mix and match as you desire.

Because each one piece island is far too small and self contained to be a supplement of its own . The only one that might be is sky pia and it covers all the sky islands