That is precisely the scenario that actually would violate the Fifth Amendment, because it forces him to be a witness against himself.

So if, for example, a person had illicit photos/documents in a safe, then the police couldn't ask them for the combination? Or if they gave the combination the evidence then retrieved would be inadmissible?

Surely it's the pre-existing evidence that [potentially] stands against the accused, not their "speech" that enables access to that evidence.

Who does such an interpretation of The Fifth protect?

As the courts have interpreted it, 5A protects you if they can't even prove the safe is yours, or if otherwise admitting that you know the combination or that you know what's in the safe would result in incriminating testimony. 5A doesn't apply here because they know the device is his, and that prior to his arrest he had regular access to it. It's not incriminating testimony, it's delivery of evidence in a criminal trial subject to a lawful subpoena.

Delivery of evidence is delivering the hard drive; changing the state of the evidence is a concretely different thing.

It amounts to interpreting the existing evidence for law enforcement.