A lot of what we know, the people in the world of One Piece do not know.
The Poneglyph related information we know iirc is this:
- We know from the Tontattas as far back as 900 years ago, Donquixote family were already exploiting them and enslaving them... so we already know about the racism and slavery history of the WG.
- Existence of Joyboy.
- Existence of a Kingdom whose name we're yet to be told - I feel VP will tell us this.
- Ancient Kingdom fought against the 20 Kingdoms, but lost for some reason.
- Before the AK lost, they distributed Poneglyphs all over the world to places like Skypiea, Wano, Fishman Island, Zou and Alabasta.
- AK had access to Ancient Fuel that could power the entire world and end wars regarding energy - knowing the WG are against equality or freedom and wanted to live like Oligarchs, they would be against sharing such knowledge or technology.
- AK had technology to enrich the lives of everyone and make the world a better place.
- AK allied with Minks, Fishmen, Lunarians (who are waiting for Joyboy/wiped out by WG), Skypieans, etc.
- Poneglyph also possess information about Ancient Weapons location.
- Ancient Kingdom had a philosophy that the 20 Kingdoms were against, and we can deduce it's anything opposite to the ideals of the current WG - WG are all for racism, slavery, inequality and control/power.
- WG seemingly wiped out many races and opposition in order to become the world power it is today.
- The World is ruled by 1 person, Imu - WG has lied to the world into thinking it's a democracy - this knowledge specifically will cause nations to lose trust in the WG if they can prove it.
I'm expecting these are the things that VP might touch on and expose to the world. We will get the gist, but we probably won't get the details.
However, I think the Void Century will specifically detail the history of the WG's atrocities before they came into power.
Furthermore, we do know the Navy is just the face of the WG - meant to make the WG look good because in reality, the WG are a deeply corrupt organisation.
They killed the people of Flevance for example, and for the world to know there's probably a 100 year history where such attrocities were rampant... will force the would to turn against the Celestial Dragons, and this is what the WG ultimately can't allow in order to remain in power.
So lies and deception is all they can use, and we won't know the true history until the SHs reach Laughtale.
Like Whitebeard said, once One Piece is found, said founder will hold the weight of history on his shoulders and this will trigger a world war essentially.
It's easy to assume because we know some of these details, that it's common knowledge, but even the existence of Poneglyph is something only known by Pirates first-hand if they get to Lodestar which Roger was the first to do.
It's after this that people decide to look for Poneglyph, and get interest in Wano and Laughtale ultimately.