I don't think of Trump as a Nazi, really, but I do think of him as a deeply sociopathic mob figure who is comfortable with Nazis and their ideology, as demonstrated by his overwhelming popularity among Nazis and his common use of Nazi propaganda and strategies. 

However, even absent any political philosophy of his own beyond his personal grievances and greed, he has been embraced by a disparate and possibly unsustainable alliance which includes:

The white supremacist tech/finance/transhumanist bro types and oligarchs like Peter Thiel, Elon Musk, Marc Andreessen, Jeff Bezos, etc...;

Neo-Nazi "SA-type" alt-right street fighting gangs like the Proud Boys, Oath Keepers, etc

Dominionist Christian and evangelical movements like Seven Mountains, YAF, etc...;

Libertarian anti-regulatory groups like the Koch Foundation and their various umbrella networks, including think tanks, lobbying groups, propaganda shops and Christo-fascist activist groups like the Federalist Society, the Heritage Foundation, the Claremont Foundation, and most of all the Council for National Policy, which knits them all together.

This is not strictly an American problem. Similar movements are rising globally, and like ocean temperatures, become a self-perpetuating feedback loop--an Assad rises in Syria, destroys the country, millions flee to other countries, which then feeds into xenophobic, fascist-styled, anti-immigration-fueled right wing movements like Marie Le Pen's in France which is currently ripping that country apart.