I don't think there's a single country in the world who would want to pay the political cost of harboring a fleeing former US President who possesses god knows what information about the US's national security.
NK would probably be the exception because they just don't give a damn.
China and Russia are smart enough to not want him once he is out the door without power.
NK though I mention as a joke could actually use Trump though to their benefit.
Have Trump there let him build a few buildings and resorts for the military a ruling class, let him live above the peasants...
meanwhile sell the message that him and Kim are rebuilding that nation together.
Bam Trump's cult suddenly gets NK a 20%-30% favorability in the US, and you have them losers trying to come there on vacation.
I honestly can't picture Trump being welcomed many places he'd actually want to live in.
I also wonder if he does go live out his life somewhere like Russia how does his lifetime secret service protection work.
Edit: thinking about it though, he could still be useful to Russia.
Set him up there and let him claim injustice, discrimination and conspiracies at his cult and keep backing it up with their cyber-ops like they have been.
It won't be as much as with him being President(30ish%) but they might keep a number of crazy people ready to do shit.