Regarding the Pledge of Allegiance, I would still argue that there's a distinct difference between an oath to a flag or the Constitution, as opposed to an oath to obey a human being no matter what. We never really had the kind of rigid, hierarchical order that existed in the monarchies and former monarchies of Europe.
We never really wanted that kind of society in America. Even the president wasn't really supposed to be as powerful as that office later became. We didn't want a permanent military establishment, although there was a drive towards expansionism just the same. During the 19th century, that was probably as close to the "Third Reich" as America got, although even that was quite different than what happened in Germany. We managed to finagle the Louisiana Territory from Napoleon, but our attempted Anschluss with Canada in the War of 1812 failed. But at least we got The Star Spangled Banner from that war. The rest of the century was dominated by expansionism, with an interruption caused by the Civil War, which in some ways might have also had certain fascistic elements, both in the Union and Confederacy.
But the overriding theme in the U.S. has been more one of commerce, capitalism, and making money. Some people might refer to America as "imperialist," which shares a good deal of overlap with fascism, but it's not really the same thing. Moreover, technically, America wasn't really imperialist since our government is a republic, and our "imperialism" is more of a covert one, using proxies and puppet governments to rule over our "empire." But even that's starting to crumble.
It's probably something more akin to high-level international piracy and mobsterism masquerading as some kind of "legitimate" democratic-republican government. Political machines, smoke-filled rooms, all kinds of corrupt shenanigans, dirty tricks, back-stabbers, shady deals - but no one is ever really completely "loyal" to any individual. Even with Trump, he seems to have a lot of people fall out who used to be part of his administration.