Having watched previous hearings in committees, the modus operandi of some of the Republicans is to use their "questioning" time simply to "testify" themselves – and not in a truthful way.
So it goes:
Questioner: "When you were kicking the puppies, did your father hold your coat in his left hand or his right hand?"
Witness: "I've ne..."
Questioner : "This email to your father in 2003 saying I need a new coat, is that because you liked getting the puppy blood on it, or because you were annoyed at it?"
Witness: "That em..."
Questioner: "Are you denying there was an email about a new coat? We have the copy here, you can't keep pretending like this."
So the point of having Hunter Biden in front of the Senate will not be in order for anyone to hear what Hunter Biden has to say. It will be for Republican senators to make rambling, unconnected, rants at him giving the emotional impression someone somewhere must have done something wrong, don't ask the details just listen to the outrage.