So, once you get past the *gasp* sex and drugs, the primary claim was that Hunter was selling access to Joe while the latter was VP. And that Joe was getting a cut. The entire basis for this is a couple of e-mails referring to some money going to “the big guy”.
There’s still no clear chain of custody for the laptop. Giuliani apparently had a copy of the data before the FBI did, and it was found shortly after released emails from Macron (maybe, I don’t remember) were positively found to have been doctored.
Ah, so this is connected directly to that pre-existing story about Hunter making money consulting for that Ukrainian energy company, probably based on vague promises of access.
I'd missed the "and Joe was getting a cut" part of the story entirely, which would explain the big deal that was made.