That would backfire gloriously. Remember - Trump was impeached twice. He was acquitted in the Senate twice. By the way - the impeachment can't fail. Either the house votes to impeach or they don't. If they do the POTUS is impeached - regardless of whether the Senate votes to convict.

Impeachment is also not a criminal conviction, so there is no double-jeopardy to prohibit charges once Joe is out. So even if he did get impeached but was acquitted, all of the evidence that was used in the house could be turned over to the new DOJ for criminal charges in 2025.

The most important point here though is an impeachment for Joe would have no effect on Hunter or his lack of a plea agreement. Even if Joe was "found innocent" there will be evidence that comes out in a Hunter trial with Joe's name all over it. That's why none of this really matters anyway.

If Hunter is convicted, Joe will likely pardon Hunter and then step down. Kamala will then probably pardon Joe for all crimes committed to date (like Pres Ford did for Nixon).

All of this assumes Joe doesn't stroke out.