For better or worse, nationalism is about the feeling that each individual is just a small part of a much larger cultural whole, and that it is the condition of the whole relative to the rest of an alien and hostile world that ultimately matters. Does Trump meet that standard?
Of course not, for two reasons. First, while it is obviously not uncommon for nationalists to reject and even demonize small racial, ethnic, or religious minorities within their country, Trump only attempts to represent about 40 percent of Americans. You can’t be a real nationalist if you despise most of your countrymen. Second, as we all know, he is purely in it for himself, and his economic policies have consistently favored wealthy businessmen over the mass of average citizens.
The bottom line is that America means nothing to Trump. He simply uses the flag like a used car salesman to sell himself.