Along with Tom Fitton at Judicial Watch, I contend that blanket pardons are not valid. One has to have been convicted of a specific crime or crimes for a pardon.
As Fitton mentioned, indict them all and let the legal process sort it out. In the meantime, the miscreants will have those huge legal costs like all of the conservatives that were persecuted along with the legal Sword of Damocles hanging over their heads. There’s a good chance of conviction and jail.
Ford’s pardon of Nixon was challenged on these grounds though it was never pursued.
Bring him up for questioning. If he has a pardon, he can’t refuse to testify. Unless he wants to contend that the pardon by President Autopen is invalid, which would be an interesting take.
So he either has to talk under threat of perjury should he lie, or claim fifth amendment rights which puts him in potential contempt land, or argue that Biden was legally incompetent.