“Nationalism” is a term with understandable baggage. Many people support their own respective nation-states, but refuse to call themselves nationalists. Many people also support equality for women, but refuse to called themselves feminists.
Thanks to American feminism, couples have the right to use contraception. Thanks to American nationalism, we are independent of the British Crown. So both feminism and nationalism have furthered the cause of liberty in this country.
Today, there are radical feminists who insist that all heterosexual sex is rape. And there are radical nationalists who insist that all immigration must be stopped. Vaginas and borders must be made secure and impenetrable, according to these folks.
But people with common sense know that most sex is not rape and most foreigners are not invaders. A woman can have a boyfriend and a country can have tourists. A woman can get married and a foreigner can be naturalized and become a citizen. A country can engage in international trade and a woman...I probably should stop right there. Oh yeah, a woman can get a job.
So in a nutshell, a border wall makes as much sense as a chastity belt. There are always ways of getting around both. They provide a false sense of security. Which is why most countries and most women do perfectly fine without either.
From a nationalism standpoint, the US is in pretty great shape. The economy is good, and the US is the most powerful country of all time. The biggest ongoing concern should be the national debt. And yet the Republican Congress and the Republican President have done nothing to reduce the deficit. A lot of their nationalist supporters are more focused on that big fancy wall and how much melanin is in the skin of immigrants.