I'd write many of your ideas are in flux. Joe Biden, for instance, is far more a Fascist than was Donald Trump IMHO. Fascism is thought to be a right wing ideology that marries big government to big business.
That's not really a useful description of fascism.
At minimum, one of the key elements of fascism was that big business was completely subordinated to the will of the state. But this is obviously not the case where big business is deciding who runs the country, because that means the state is being subordinated to business. Fascism is really a form of authoritarian, extreme nationalism.
Biden is very plainly not a fascist.
Trump, however, it gets a bit trickier.
The history of fascism is to see fascists playing on the fears and unhappiness of a societal majority, usually by telling them they are under threat, that something has been taken from them, and they are the only people who can fix it. This is invariably conservative-linked because it plays on the past: "You had it so good, then X ruined it - deal with X and you can have it back". Nationalism is the obvious vehicle for this: the sense of national values and national history for the societal majority - their traditions and their beliefs. And X of course naturally becomes the scapegoat, the Other, that must be controlled, defeated and stamped out.
Trump, bluntly, was fascistic. You can see in him all the tricks that fascists used in their rise to power. It's this idea of harnessing a societal majority (white people) with a feeling of being threatened or becoming victims, presenting them with an idealised view of the past that needs to be restored ("Make America Great Again"), and an othered enemy that's causing all this woe (mostly immigrants). Trump then presents himself as the only saviour, assaulting any resistance - even his own party where it failed to suit his ends.
His attempt to subvert the 2020 election is really just the icing on the fascist tactic cake: someone prepared to construct a "big lie" to maintain their power at any and all costs. Fuck democracy, fuck the country, take and hold power. When we talk about lying, note Hannah Arendt's quotation: "Fascists are never content to merely lie; they must transform their lie into a new reality, and they must persuade people to believe in the unreality they’ve created. And if you get people to do that, you can convince them to do anything." Trump's constant lying, and the support of the further elements of the US right wing media in that, cannot be taken without that context.
This attempt to steal an election is also indicative of Trump's authoritarianism, although Trump had made his authoritarian inclinations clear in so many ways before that. This authoritarianism is something his supporters determinedly overlooked, because they never really opposed it. They wanted a "strong leader" who would kick those pesky democratic institutions aside and do what needed to be done, who would crush the media, naysayers in Congress, the government bureaucracy, etc.
If we wanted to ask did Trump govern like a fascist, the answer is no: Trump was pretty inactive. He didn't really have an ambition for the country, he just wanted to be at the top without much desire to do anything with it. But he clearly used the fascist playbook to get to the White House and to try to stay there. He proved that the rhetoric and tactics of fascism works to get elected in the USA, and that's why I would call Trump a
proto-fascist. The fact that these have been so effective within the Republican Party means they are probably here to stay for quite some time. The USA just needs to hope that until this phase goes away, no future Republican candidates have fascist policies to go with the fascist rhetoric and tactics.