Republicans don't give a sh!t.Witnesses will put it all out there. It can show (potentially) that Trump ordered the SecDef to tell the NG to stand down. It could show that elected officials communicated with rioters, that rioters believed Trump was on their side, etc. Make the Republicans own this by voting for acquittal.
Also, all of that stuff you're talking about is for a criminal investigation. Impeachment isn't a criminal trial, it's a political one.