I'm asking for what you believe--so I can't really have a problem with your answer, as long as it honestly reflects your beliefs.
So, for you, a Christian Nationalist (in America) is just a person who wants to put the best interest of American citizens above all others and who is also religiously a Christian? I think based on that definition, you could have a pretty big camp, including people who might want a very secular government. That is different than the Brittanica definition above.
But I'm not quite sure why, with your definition, you'd even add the Christian part. If the former doesn't inform or affect the latter, why not just be Nationalists and be done with it? (For example, with your reading, do you think White Nationalists and Black Nationalists are different in a ideological sense?).
I guess a question that different people who think of themselves as Christian might answer differently is: does being a nationalist conflict with the teachings of Christ?