I couldn’t figure out a way in Brave, it won’t let you set a custom URL for the default browser. Firefox allowed it to just change the customer browser link in the format of

Couldn’t find an APK to test vanadium, I assume it may be exclusive to GrapheneOS? (I just called it test for this, so name it something you’ll recognize in a few months)

Once the Default browser is changed in Firefox/chrome, their widgets pull that information from the app, so it just searches that way.

Yeah, the chrome one will convert.

If you set it as your default search in chrome or such, it will convert the Google search bar in Android to a SearXNG search bar. I started using it a little while back. Firefox never did well for me on Android (I’m sure it’s anecdotal)