Thanks for asking for my perspective, happy to offer it:
(1) Can you clarify what you mean by "bottom"?
(2) What do vivre cards indicate to you?
(3) 2 sides of the same coin?
First of all, I really like the way you formulated this. I do think it would have been helpful for you to give a little more detail per bullet point though. I don't think the One Piece is as simple as something which gives society information or something like that. One of my original theories was that the One Piece would somehow transmit information to all living people and that it would be so damning that the entire world would openly revolt against the CDs. But as the story went on, specifically the stories of Doffy's past, we saw that every day citizens already understand that the CDs are scum. There is no convincing to do. They are wretched and everyone knows that. This is part of why Sengoku is a worthless coward.
So based on the story since then, I don't think the One Piece is history. I have considered a mass amnesia event (don't reference other series in response to this, per server rules) but it has the same flaw: Everyone already hates the CDs.
The only information that I think could be legitimately problematic for the CDs is if there is some key to transcendence or space travel that people simply need to know about. If there is some type of power or something that people just need to hear of to gain, it is possible the CDs were able to remove this power from the global population through some method.
I think someone in this thread mentioned a connection between whales and music and I think that is really good and I actually
'd when I read that. I think it is really, really worth focusing on. Whale music/sounds/communication is significant and I think it really does relate to something involving Joyboy or whatever. We got a pretty big hint of this from Laboon latching on to Brook's crew at an early age. I think music can be used as a form of taming of whales. And as we have seen, whales can be truly amazingly large, similar to seakings but smaller than the "super sea kings" that appear to have VOAT.
The Red Line prevents whales from spreading their song across the world. I wonder what the song did. When Luffy got the whole Hancock kingdom to dance and sing with him, it was significant and definitely an example of a unique power. It feels like, based on what we know, Joyboy has some kind of unique ability to inspire/influence people with music or song or dance. Seems easy to relate to whales when we already know the seakings referred to the FEELINGS of whales. We should keep in mind that whales seem intelligent.
An important question: Who do the whales miss, what did their song do, who did whales like listening to previously? Perhaps Joyboy tames whales through song the same way Shirahoshi does with Seakings.
It is possible none of that relates to the one piece but i think it might be a requirement to get it. I'm just not sure how it would work. I have nothing really to relate whales to the one piece. We know that Roger reached Laugh Tale and seems to have found the one piece, but it isn't clear that he was able to use it in a meaningful way. Maybe it needs whales. Maybe it is similar to how it appears seakings are necessary to pilot Noah, perhaps whales are necessary to utilize the one piece. I think it is possible that Pluton requires whales in some way, similar to how the Hancock kingdom uses those dragon things.
We know that King's race was wiped off the red line. We don't know of any other races that live on the red line other than the CDs. That is super suspicious because its unbelievably large. It should be possible to hide something ON the red line. I am confused by King's race being wiped out. I am assuming other races either used to or still do live on the Red Line.
One of my theories is that the Red Line was the only natural part of the planet and the islands are from destroyed moons