Just by comparing the position of the GOP with some positions of, say the AfD and the former FN (Germany and France respectivley), I could make the case that right wing parties have a much smaller voter base in these two countries then the US.
I don't think it's useful to conflate anything right of center with fascism. I was thinking of parties like NPD or Golden Dawn, which aren't just "right wing", but thinly-veiled Neo-Nazi parties, attracting hundreds of thousands of votes.
The NPD all but ceased to exist in the last couple of years. The AfD had one internal group dissolve itself because it was classified as an unconstitutional radical group (Der Flügel). High ranking party members want to shoot migrants and are borderline denying, yes, the Holocaust. Right of center would be parties like the CSU and the right leaning part of the CDU.
Where is the evidence that this is true? Sounds like wishful thinking to me.
In many European countries, Holocaust denial is literally a crime, yet de-facto Neonazi parties are more popular than in the US, where no law stops you from brandishing a swastika flag.