There are at least two things that distinguish the contemporary GOP from far-right, ethnonationalist parties in Europe: 1) the GOP is (in theory and practice) anti-majoritarian; 2) the GOP remains ideologically opposed to the welfare state, even for the Herrenvolk.
In Europe, parties like Poland's ruling far right Law and Justice Party have greatly expanded the welfare state. They won in part as a reaction to neoliberal policies of center-left or (as in the case of Poland) center-right parties that reduced the size of the social safety net.
In the late 20th century, the U.S., too, saw its center-left party join its center-right party in whittling away our welfare state, which was already smaller than those in most European countries.
On a purely rhetorical level -- departing from previous GOP presidents -- Trump will occasionally express support for an enhanced social safety net. Witness his promises in 2016 to improve Social Security or offer a better healthcare plan.
Most recently, we saw a small flurry of such rhetoric in yesterday surrounding the Executive Orders (most of which were not, in fact, even EOs) purportedly responding to the economic crisis he helped create with his failed pandemic response.
But unlike, e.g., Poland's Law and Justice Party, the GOP, even under Trump, remains a party that, in practice, remains deeply committed to deregulation and the tearing down of the welfare state.
All of Trump's promises about healthcare and strengthening Social Security have been, predictably, empty. Instead, his administration has tried to destroy the modest improvements in healthcare brought about by the ACA, first in Congress and now in the Courts.
And the most significant part of Trump's most recent round of economic policies -- a cut to the payroll tax -- is yet another Republican assault on Social Security and Medicare.
Both of these aspects of U.S. neo-fascism -- its (typical for the global far-right, but atypical for the GOP) promises of a social safety net for the in-group and (atypical for the far fight, but typical for the GOP) actual opposition to such a safety net -- are significant.
And they are in some ways related to that other big difference from Europe's contemporary far-right: the GOP's deep hostility to majoritarianism.
Again, even here, there's a lot that's typical of the far right in the GOP. Far-right parties tend to argue that their nations are under existential threat from forces external to them. (This was the role that Jews played in Nazi ideology, of course).
The imagined threat of a global LGBTQ conspiracy is very important to the Law and Justice Party's rhetoric in Poland. And more generally, Law and Justice presents Poland as a nation ever under threat from such outside forces throughout its history.
This sort of political understanding is absolutely central to the GOP. The idea that white, Christian America is under siege -- from immigrants, ANTIFA, Jews, Blacks, college students, Democrats, Marxists, you name it -- lies at the heart of contemporary Republican politics.
But there's a huge demographic difference between the US and a country like Poland. Ethnic Poles are the vast majority of Poland's population (96.7%). The percentage of Polish citizens who are Catholic is almost as great (92.9%).
But, in the United States, white Christians are already in the minority. And their percentage of the population are likely to decline in the future.
This demographic situation in the United States is, in a sense, politically convenient for far-right conspiracy theories about threats to whiteness and Christianity.
But it is politically inconvenient insofar as the far right already cannot win national electoral majorities in free and open elections in the United States.
Luckily, for the American far right, there is a deep American tradition of anti-democratic thought into which it can tap. The writings of John C. Calhoun are arguably the greatest distillation of that tradition. And the Confederacy remains its most significant experiment.
Two of the states that attempted to secede in 1860 and 1861 -- SC and MS -- had Black majorities. But even those that did not had white populations that were overwhelmingly poor. Most Southern whites couldn't afford slaves and were (potentially) threats to the planter class.
The ideology of the Confederacy was not only explicitly white supremacist, but also more generally hostile to democracy. And Calhoun's rejection of Enlightenment ideas of human freedom and equality extended beyond racial hierarchy. This is from his "A Disquisition on Government": 
The U.S.'s founding documents -- the Declaration and the Constitution -- are obviously much less hostile to these Enlightenment ideas that Calhoun railed against (and that Confederates like CSA VP Alexander Stephens in his famous "Cornerstone Speech" explicitly rejected.)
But the Constitution nevertheless has deep strains of anti-majoritarianism in its structure, e.g., in the apportionment of the Senate and the electoral college.
For his part, James Madison, in Federalist 10, e.g., expresses concerns about majority factions. But his solution is not minority rule, but rather a complex Constitution that, he argues, forces the formation of cross-faction governing majorities that will pursue the common good.
Even John C. Calhoun wrapped his deep antimajoritianism in rhetorically majoritarian clothing, arguing for rule by what he called a "concurrent majority" (which was actually a scheme to give minorities like the slaveholding South veto power over national measures they disliked).
Nevertheless, like a loaded gun carelessly left in a living room, our political tradition's and political system's antimajoritarian strains are ever present for use by those hostile to democracy. And in America today, nobody is more hostile to it than the GOP.
This is anything but new for Republicans, of course. Going back to the mid-20th century, the highly partisan and largely nonsensical and historically illiterate claim that the U.S. is "a republic, not a democracy" has been a key part of GOP rhetoric.
But in more recent decades, the Republican assault on, e.g., voting rights has intensified (among other things, this reflects the fact that, between the '50s and today, the white South has flipped from overwhelmingly supporting the Democrats to overwhelmingly backing the GOP).
The GOP's explicit antimajoritarianism can be found across the party. Even supposedly thoughtful and moderate GOPers like NE's Ben Sasse peddle in it:
"If we had to unpack American political philosophy in one word, I think it's 'antimajoritarianism'"
"If we had to unpack American political philosophy in one word, I think it's 'antimajoritarianism'"
All of this makes the GOP's version of far-right ethnonationalism a little different from that of the contemporary European far right. Both in practice and theory, the GOP defends not a (supposedly) beleaguered majority, but a (supposedly) beleaguered minority.
And though Republicans do like to talk as if they represent the views of most Americans, their absolutely explicit hostility to majoritarianism and their equally explicit attacks on voting rights kind of give the game away.
