Too much to address here and I don't have the time. But you are jumping around a lot and conflating culture war nonsense with legal enforcement. While also implying huge swaths of people are right wing nazis....
Harry potter has never EVER been banned in the USA and to say that with a straight face means we are in completely different universes and further engagement is pointless.
Many groups may have lobbied a retailer or a local school or library to voluntarily remove it. Even just to avoid drama/pr. I personally vehemently disagree with this type of censorship... But it is absolutely not what we see in the UK. The US equivalent would be federal terrorism charges for having harry potter. Absurd.
That jhst highlights the difference. In Europe people are concerned about whether something is available. They aren’t interested if the book was banned by a federal government or a school librarian, it’s still banned.
American view is that private companies banning something or spying on someone is fine as long as it’s not the government doing it.
It comes down to the accountability. Europeans tend to believe in the ability to hold large organisation to account via the ballot box, Americans prefer the free market.
What we see in the U.K. is a view shared by most people that incitement to violence, glorifying terror etc is illegal. Americans are happy to have Musk or Zuck do the censorship instead, with them being able to use their wallets to hold them accountable.