What will he testify to? That he told Trump he lost? It doesn't matter. What matters is what Trump believed.
He can be behind bars and be president. He will be convicted on any case that goes to jury. Appellate level perhaps including SCOTUS is where the cases will be won unless they are thrown out prior. He can pardon himself on Fed charges and although not tested, it is my view that he can also pardon himself on any state charges owing to the Federal Supremacy in The Constitution.--So, he won't be behind bars after becoming president.
Pfft. So much wrong here it’s almost exactly wrong.