The claim obviously is this was some "sweetheart deal", but the somewhat similar cases I've read about aren't all that similar. I can't discern whether he got a break or not, personally. There is prosecutorial discretion that goes a long way in such cases. It need not be partisan, though it can be.
Hunter is still under investigation for other matters.
It's clear to me none of this is about Hunter at all, it's about Joe, and Republican hopes they can drag him down with this stuff. The odd thing is if they somehow manage to do this and he can't run in 2024, the Democrats have arguably stronger candidates in the wings. As a political strategem, it might be premature.