This is a huge reach and false equivalency. There is a difference between being a pop culture focus of a moment where you're mom was compelled to volunteer at his local election office and wear a button versus the maga bullshit that OP describes.

No. It's never been to this level, or close for that matter. Not because a candidate didn't want it, but because society maintained a basic level of decency and civil education that made today's depths impossible at scale really. Of course a huge focus of the last 50 years for Republicans has been denying access to and attacking public education to help form the undereducated and easily frightened mass that they now use to support trump. And then social media feeds and predatory news algorithms were probably the nail in the coffin to break that once held floor of civility.

Not on the same scale as trump, but there was an American Nazi party and there's the kkk. Those are probably your closest analogies in this country.

Even the attempted Trump assassination, which generated considerable tin-hat response, is now almost completely forgotten; certainly, nobody’s talking about it in mainstream forums.

Well yeah, that's how attempted assassinations work. People don't remember the ones that don't work, they remember the ones that do. If it did succeed then it would be all anyone would talk about. The outcome is what matters in these situations, and greatly changes when and how people talk about it. That's just how these things go.