@Daz I strongly disagree with your take on Robin and archeology. Archeology, in its essence, is to go around and listen to voices of the past. That's what the Poneglyphs themselves are.
Robin went to Alabasta and discovered Pluton's location. Then to Skypiea, and discovered Poseidon's location. Then she confirmed it with the father of the current Poseidon, himself the holder of centuries of "secret knowledge" passed down in the royal family. Then, in Wano, she actually found Pluton, again by tracking down secret knowledge passed down in generations. That's mostly what archeology is: why does it matter if it's a guy telling Robin a generational secret, instead of a stone tablet she finds and reads?
About Vegapunk: he knows what Ohara knew, because he stumbled upon it as a scholar, and he inherited the ancient technology.
Like, Robin knows so much more than him right now. Vegapunk seems to have 8 year old Robin's knowledge about the Void Century. For instance, does Vegapunk know where the ancient weapons are located? I doubt it. Now, if it turns out he does, well you're right.
I mean, your point does apply, and strongly so, to the Road Poneglyphs and the One Piece adventure. The crew has never been to Lodestar, and that potential amazing reveal... was a conversation in Zou. But not to Robin, I think.