There is no reason to pardon Hunter, apart from "leaving in good terms" by the Bidens as a goodbye gift.
Joe is about to cross the threshold and have his last trip behind the barn. You get the idea, very romantic, sweet and wholesome; dying with his family around him and such. And they lived happily ever after, etc...
Sure.
But that would be purely motivated by a sort of quasi buddy-buddy thing. That will cause, if not outrage, but huge incomprehension and frustration from regular Americans.
Hunter's crime is not controversial, it is not special, it does not hold any kind of legal conundrums or anything. The dude is a drug addict, who did tax fraud, got involved with prostitution, violation of several ethical things, etc...
Though they are a big deal because of his lineage, these things are basic stuff. Lots of people do drugs, have a gun when they shouldn't have one, cheat on their taxes (taxation is theft) and all the things he has done. Some of them have done these at a far lesser extent and yet got slammed excessively hard.
Just look at how Kamala treated people busted with a few grams of funny lettuce on them.
There is no reason why he should be exempted.