Well, in some European countries it is common to elect in office persons who earlier had public posts like PMs, Minister of Foreign affairs etc....Hmm, I haven't yet met an American voter who cast their ballot on this attribute exactly. I think he'd be a tough sell to them having not held public office or been successful in business. Lots of folks with lots of politcal experience are terrible in front of crowds or in interviews or photos etc but if we voted based on gas tank he would win I guess.
Ofc I agree that president should have also popularity in his own country.
While in international scene both Trump and Biden are very boring and looks like predictable half lethargics , sorry for real point here.