It would be awesome if someone could create this addon for Firefox.
I use it almost every day on Google Chrome.
You just put a backslash before your search query, press the return key, and it will automatically redirect you to the first search result. Sooo useful.
There seem to be multiple search engines for Firefox that use Google’s I’m feeling lucky. You can define a keyword to trigger the search engine in the search preferences (type about:preferences#search in the URL bar to get there).
Found this one: https://addons.mozilla.org/en-US/firefox/addon/google-feeling-lucky
Works well, but no support for opt-in with a leading backslash.
I could look at the others: https://www.google.com/search?q=“feeling+lucky”+firefox+search+addon
But I’ll just stick with the first one for now.