An argument could be made that there is a lot of ideological overlap between current far right GOP/Qanon people and the tenants of Nazism. Considering the number of elections won by the GOP you cannot tell me they're not mainstream.

There's a lot of overlap between the Nazis and both major parties in the US. That said, I don't think it is fair to say that being a Nazi is mainstream because there is some ideological overlap.

It just means that some parts of their platform have become mainstreamed. A simple and non-controversial example is that the Nazis were extremely Progressive on animal rights. Just because modern political parties also endorse animal rights, that does not make them Nazis

Another example is that Nazi rhetoric relied heavily on utilitarian analysis of the greater good. I don't think it's reasonable to say that any party that promotes the greater good over individual freedoms is a Nazi party.