You don't just need permission for a demonstration in Germany if you plan to block traffic. See e.g. how covid policy protesters were treated. But I guess you agree with those policies so think that's ok.
covid was a special case, because obviously a mass gathering in that time would have been considered a health risk. a lot of countries went into emergency mode and used exceptions to implement or enforce these rules. they are not a good indicator of what is normally acceptable and allowed.
just because something was possible to happen during covid does not mean that it is possible to happen otherwise. comparably what is happening in the US now is also exceptional and we have yet to see if that becomes the new normal.
btw, it turns out i was wrong, you don't even need permission, you just need to announce the demonstration. there can be restrictions, and in specific circumstances a demonstration can be disallowed. but by default all you need to do is make an announcement towards the appropriate institutions.
