Not wrt Trump, per se, but any discussion of Republicans or conservatives by those sufficiently left of center has the words "facist" and "fascism" hanging on the speakers' lips. It's virtually a general term of abuse with an arbitrarily low bar for application.
Trump's fascist. Bush II was fascist and there were already concentration camps set up for the population. Bush II was a fascist. Reagan was a fascist. Nixon was certainly a fascist. Ford, a crypto-fascist. Eisenhower, fascist. So was Coolidge. And Harding. Meh.
The guy who rounded up people based on their race and put them in concentration camps? He wasn't a fascist. Nor was the guy who dropped the A-bombs. Or suspended habeas corpus. We like them, so they're okay.
There have been precisely one fascist state and one Nazi state. They viewed themselves as different. We view them as the same and apply 'fascist' as an exonym to both. Which were their defining characteristics? I've seen lists of 2-3 traits, lists of 20+. Depends on who you talk to, and that usually depends on who they want to call "fascist" at the time. Some of the longer lists have traits that apply to Obama more than to Trump. Nobody used those lists then--but they were all the rage when Bush II was around. The definition's fluid, so fluid that the term really is just a term of abuse. We find the target, and then change the meaning to make sure it applies. Yeah, that works. Not.
Snyder's trying to sell a book while proselytizing his views. I take him as such.