I know the talking heads are saying that because DJT is a first time offender, he will likely not be incarcerated. But then the sentencing judge is Merchan, the same one who handed Trump $10,000 in fines for violating his gag order. And what he said when doing so is the interesting part:
"Because this is now the 10th time that this Court has found Defendant in criminal contempt, spanning three separate motions, it is apparent that monetary fines have not and will not, suffice to deter Defendant from violating this Court's lawful orders."
Given that the judge is cognizant that fines mean nothing to DJT, perhaps he will wish to sanction him by other means. That could mean imprisonment. But not before the election. Trump will surely appeal the verdict, avoiding any immediate consequences until well after November 5th. If there's one thing Trump is good at, it's delaying tactics. Thankfully, he will not be able to pardon himself if elected. Only the Governor of NY can do that.
Under NYS law he could still send him to jail even before sentencing as retroactive punishment for the gag order violations too. It's not either a fine or jail, it can be both. And he can chose to do it at anytime during proceedings like at the end if it meant the conviction stage would be expedited. This cannot be appealed as it's a bench judgement for being out of order. It would likely just be for a day or something.
Assuming that the current Democrat holding the office (Kathy Hochul) is not replaced by a Republican (fat chance), I doubt any amount of coercion would result in a pardon. Coercing a public official is also a felony, and sitting Presidents can be tried for state crimes. Never happened before, but DJT has been busting that mold.
Pardoning is done at their sole discretion. There is nothing illegal about bribing for a pardon. Trump could easily have a SPAC say "hey, here's $500m, pardon him and retire." Political suicide for sure. But not illegal, there is precedent, and if there's life changing money (maybe a fraction of that) there's a possibility.
Keeping a political donation for personal use is illegal, as is bribing a public official. They might offer a highly paid position to get around it. But as you say, it's political suicide, and if the money went to the Democrat party, as it did with Marc Rich, the party risks a big black eye as well.