They were investigated by Bill Barr's DOJ when Trump was in office, and they found nothing. Since then, Hunter's business partner has testified that Hunter sold the "illusion" of access, and when Joe was on phone calls with people Hunter was dealing with, they did not discuss business and often Joe was not even told who was on the phone.
This is just Trump pushing the Freedumb Caca which is pressuring McCarthy to do this or face losing the speakership. So McCarthy is launching an impeachment "inquiry" because he doesn't have the votes for an actual impeachment. And even if he did, it would be certain to fail in the Senate.
This kind of performative drama is loads of fun for you people but will have no more effect than the Trump impeachments. And for the record, those turned out to have been total wastes of time. If you want Biden out of office, vote for his opponent next year.