I listened to the oral arguments several times. John Sauer did a great job arguing for Trump. The federal attorney (they didn't us the Solisitor General, she got her ass handed to her by the young Jeff Green on Fisher vs the USA) didn't do that well. Katanji Brown appeared to side with Sauer's arguments but did mention sending it back to the Appellate Court. Sauer argued that the Constitution and the Framers said the President stands alone in the Republic and MUST HAVE immunity while conducting government (official) business. If the President would act solely (personal) for himself there is no immunity.
Is sent back the Court of Appeals is going to have to do something it's never done, prove Trump's actions that they found him guilty were personal. It's going to be very interesting for sure.