My impression is that the original question can be understood in at least two different ways and this leads to many posts constantly missing the point of the posts they're replying to.
The first interpretation is pretty straightforward: What if the citizens of other countries could vote in the US presidential election while still remaining citizens and inhabitants of their own country. The answer seems pretty straightforward: There are polls, you just need to look at them.
The second interpretation is much less straightforward:
- You could ask how many citizens of other countries would vote for Trump if they were Americans
- You could ask how many citizens of other countries would vote for Trump if he ran for head of government in their country.
The answer to the questions of the second interpretation can be a funny exercise, but it depends a lot on the exact question.
Meh.
I don't think the answers to the second interpretation would be meaningfully different from those to the first, unless:
in case 1) you assume that the citizens of the country of choice had been Americans all their life.
in case 2) you assume that Trump reshapes his platform to be fitting to the country of choice. I'd argue that some meaning would be lost in this case, though.
My main point was that statements like "Trump would win the Veneto" don't make a lot of sense without a specification of the scenario in the first place.
But I think that nationality, citizenship or the place you live in can fundamentally change your opinion of a politician, particularly if that politician is a nationalist or even is hostile against your country.
Platform reshaping or not is an interesting question. Would Trump benefit more from reshaping his platform than Biden? Why? Because Trump is more nationalist on certain things?