I don't think that the sarcastic dismissive "You know Trump and Hitler both did <insert overwhelmingly common thing here - like they both had a sandwich" as a rebuttal against the "Trump is a Nazi" claim is a particularly effective one.
I get the point people are trying to make when they do that, but it's not particularly helpful in that it feeds into the left's talking points about "we take things like Nazism and fascism seriously and the other side doesn't take it seriously at all"
I think it'd perhaps be more effective to discuss it within the framework of the following two realities:
1) Every form of "authority", exercised to its full extent, would become "authoritarianism". Even forms of authority that people purportedly see as "good" would become seen as "bad" if the dial was turned from a 2 to a 10. (IE: "having police" = 2; "police state" = 10)
2) Every form of "nationalism", embraced to its full extent, can turn into fascism in the form of what people have labelled "othering".
We all have at least a certain level of both authority and nationalism we embrace. For instance, I like that we have things like police, a system of governance with checks and balances, and I like the fact that the US is its own country with its own (different) laws, cultures, and priorities.
So, one team saying, "Trump is like Hitler", and the other team giving a dismissive rebuttal in the theme "well everyone who drank water is like Hitler, cuz Hitler drank water" is missing the forest for trees.
The reality is, we all exist somewhere on both of these two spectrums.
The spectrum of "anarchy <-> totalitarianism", and "multiculturalist <-> nationalistic"
It's the old analogy of traditional light switches vs. dimmer switches.
If we pretend that those spectrums are represented by values ranging from 0 to 10...
And, if we pretend that Hitler represents the "10's" on both spectrums, what level does a person have to reach on those spectrums before it becomes a cause for concern, to the point where it's even worth drawing comparisons? and what objective metrics should be used to assign those values?
...because, as I noted, none of us is a 0 on either.
So the question is not "is Joe Shmoe like Hitler?", it's "to what degree is Joe Shmoe like Hitler?"
I know it's uncomfortable to think of it in that context, but that is the reality.
Merely by preferring that you'd prefer we delegate certain powers to the federal government (no matter how limited), and merely acknowledging that (culturally speaking) you'd prefer to reside in certain places over others, you're already on the "0 to Hitler" spectrums.