Specifically, he's charged with illegally owning a gun while using an illegal drug (crack).
While I am on the fence about the NY Trump case, I do have a clear view on this Hunter Biden case: what he is accused of should not be a crime.
I oppose the War on Drugs and support broad gun rights. It should not be illegal to use the drugs Biden used, and it should not be illegal to own a gun if you are a drug user. I'm open to laws that ban carrying a gun while you are high (just as you also can be forbidden to drive a car while in that condition), but not to categorically denying drug users their Second Amendment rights. Should Hunter get convicted, he may have a solid Second Amendment argument to overturn the conviction (though the relevant Supreme Court precedent is admittedly vague).
Cynics will say I am taking this position because I want Hunter's dad to beat Trump (which I do!). But my positions on both drugs and guns are longstanding.
I also think that Hunter is a grifter and a slimeball. Among other things, he's been trying to get out of paying child support to the little girl he fathered out of wedlock, and to prevent her from bearing his last name. Trump is a much worse person, and unlike Hunter he is actually running for president. But that doesn't excuse Hunter. You can be a terrible person, even if you are not as bad as Trump.
Regardless, I think Hunter should not be punished for the behavior at issue in this case.
Finally, it's worth noting that the Justice Department is pursuing the case aggressively despite the fact that Hunter is the president's son. Would a Trump DOJ be similarly willing to prosecute a member of HIS family? The question answers itself, and highlights a notable difference between the two candidates.