Conservative groups influential with the Trump administration have pressed for the preemptive acts of clemency.
There’s a world of difference between a pardon issues to prevent malicious prosecution for non-crimew and one issued to people you’ve been instructing to commit crimes
and you can’t use the 5th amendment to refuse to answer about things you’ve been pardoned for, because there’s no risk of self-incrimination if you’re already pardoned for any potential charges
Indeed, so someone who has been pardoned federally can be compelled to testify to their crimes.
The really interesting part: When federal crimes have state criminal implications, that means during testimony, they either commit perjury by not being truthful about the crimes, can be jailed for contempt for refusing to answer, or they are truthful and while some conduct will be covered by the pardon, there’s a good chance testimony can be used to inform other non-pardonable state crimes.
Now, the question is whether anyone in positions of prosecutorial power has the guts to push, or instead will give up before trying. But they definitely can.
Most likely, if they can demonstrate that there might plausibly be some state level criminal liability they’re not immunised for, then they still get to use the 5th amendment to avoid answering.