Brave Search (Tor Onion) by Mike Tigas

This adds the Tor onion site version of Brave Search to the browser search engine options.

After installing this addon, you can go to the Search section of your browser settings to set "Brave Onion" as your default search engine.

Note that you must be using Firefox over a Tor connection, or Tor Browser, to be able to access the onion site.

The source code for this extension can be found here:
https://0xacab.org/mtigas/firefox-brave-onion