It's far less trivial that you are implying, there's way less data about a Libra account on the ledger than there is on your web browser when you visit a page.

It's far less trivial that you are implying, there's way less data about a Libra account on the ledger than there is on your web browser when you visit a page. But I'll grant that it's not impossible, just wayyyyy more expensive and more trouble than it's likely worth. Especially since most Libra users (at least at first) will already be using Facebook app or Whatsapp as their Libra wallet, which they can of course get data from.