Stupid. A mistrial means none of that happens.
A post verdict mistrial may be granted for only a portion of the jury's verdict, and a final judgment entered for the rest of verdict, if the reason for the mistrial does not require a mistrial as to the entire case.
Your ignorance of that fact does not make me wrong, much less stupid.
Could the decision to enter a final judgment on some counts, and retry Trump in a few weeks on the other counts, be challenged? Sure. But until Trump got a higher Court in New York, or a Federal Court, to stop it, he would still be under the gag order, and compelled to appear in court whenever the trial judge wants.