> If their digital forensic experts haven't found evidence of foul play
We only know the FBI subpoenaed the laptop because it was leaked to Fox News. The leak itself is presumably accurate, but we have no information about what the FBI did or did not find on the laptop – except for a letter that they have "nothing to add at this time" to an appearance by DNI John Ratcliffe on Fox Business.
In that appearance, Ratcliffe (a highly partisan official) did claim that the laptop was not part of a disinformation campaign, but also said that "I know so little about those emails and what is apparently on Hunter Biden's laptop". So it seems like he was referring to a lack of information about the laptop from the intelligence community rather than inside information from the FBI.
Admittedly, the FBI generally can share information with the intelligence community, and apparently in this case it has not. That does suggest that they probably don't have e.g. evidence that a specific foreign actor was behind things. But we don't know whether they've found evidence that foul play in general occurred or might have occurred. Heck, it's even possible that they found evidence of foul play by a specific entity, but didn't send it to the intelligence community because that entity is American – though I wouldn't say that's likely.
As for the lawyer, the closest we have to hard evidence is a screenshot of an email apparently showing that a lawyer for Hunter Biden spoke with the repair shop owner after Hunter was presumably asked for comment by the Post; it doesn't show any specific claims made by the lawyer. Beyond that we just have Adam Housley and Rudy Giuliani relaying the claims of the repair shop owner. Leaving aside those sources' lack of trustworthiness, Housley himself claimed that the attorney had the wrong year for when Hunter dropped off the laptop and "didn't even know when he left em there" [1]. If anything, that suggests that Hunter doesn't know the provenance, though it's hard to say without more information.
[1] https://twitter.com/adamhousley/status/1317319606126604288