Being a Nazi is not only not banned in most countries, in some like the US it's explicitly legal (i.e. "Freedom of Speech"). That said, it is (kinda) banned in Germany, yet they are still around over here, because you can't ban people from believing in stuff.
All a state can do is to try and prevent them from gaining too much traction, and I do not feel like Zionism has all that much tbh. Israel's recent actions are very unpopulat in the west, even though most people are not even affected by them in the slightest. Many of the people who protest them probably have no direct connection to Israel or Gaza. So what's the goal of a ban even?
I can only speak for Germany, but here an Israeli sniper and alledged murderer fled the country, bacause he is being persecuted for warcrimes, i.e. the murder of civilians. You also cannot call for the extermination of anyone without riscing consequences. This does not prevent people from being Nazis, Zionists or anything else. It just sanctions them for publicly expressing it.
Yeah, what a terrible idea to (quite loosely actually) regulate something that definitely needs to be regulated, and to do so before you wasted billions on it, since you can't wait to shove that shit down everyone's throats. Not your own money of course, oh no. You fill your fucking pockets with the money of delusional and/or clueless investors, because hardly anyone is paying for said shit.