If Trump’s kids were ever charged he would definitely pardon them. Therefore, even though it would be wrong, Biden would be morally justified in pardoning Hunter because we All know Trump would do the same…Plus, it would be an awesome way of giving MAGA the middle finger. Unfortunately, Biden is a decent man who respects the rule of law so the scenario you are describing will never happen.
Maybe, though, if Trump wins the election in November but then Biden kicks the bucket before Trump gets sworn in…maybe then Kamal Harris could pardon Hunter on her way out the door as a final Fuck You to MAGA?