Smith is prosecuting Trump for his personal actions as opposed to his official presidential actions. He has complete authority to do so. There is nothing unconstitutional about his charges or the prosecution of the case. If, as you claim, he didn't have legal authority to continue the case the courts not only wouldn't but couldn't schedule hearings and hear the case. Your conspiracy theory crap doesn't supersede the actions of the court.
The claim is that merrick garland didn’t have the authority to appoint smith as a federal prosecutor because he never went through the advice and consent process. It doesn’t matter if this was a presidential or personal issue for Trump, what matters is, was smith legally appointed as a federal prosecutor as a special counsel to do this case.
This is a federal case.