If you're using DuckDuckGo, you can also just add sites you don't want to see in your results to the block list. Other search engines may have a similar feature too
nixos
All about NixOS - https://nixos.org/
I run searxng locally and there is hostnames plugin ( https://docs.searxng.org/dev/plugins/hostnames.html ) to replace, remove or give high or low priority.
In Firefox and its forks, you can define "bookmark shortcuts". Usually short names for websites that act as commands that take you there. I have some three-letter shortcuts for different pages on the same domain that would otherwise lengthen into the wrong default page.
Bookmark a page, then open the bookmark in the bookmarks manager and set the shortcut property.
In your case you'd bookmark the official wiki and then set its shortcut to be the unofficial wiki's URL, so it would treat it as a shortcut to the correct one instead of an address to the incorrect one.