Maybe if Merchan orders Trump to prison the Supreme Court would stir itself to get involved. Maybe.
I personally believe that even if Trump is not sentenced to a jail term by Merchan, an emergency app for a writ of cert would be accepted by the SC to resolve the appeal before the election. There is way too much reversible error in that trial for the appeal not be accepted by a Republican court. If the court was 5-4 Dems, it would be denied on a political basis but the 6 Republicans on the court are not blind to what Merchan was doing. I don’t think the Dems will have the convicted felon narrative to use going into the election after the SC reverse the conviction