This wouldn't let you use multiple "flavors" of Brave though unless they expose different URLs for 'Goggles'; sounds like you just are allowed to enable one as a sitewide setting.
They do have different URLs for different goggles. Do a search for the word "test" with a Goggle on, then grab the URL from the address bar and paste that into your new bookmark. Replace "test" with "%s", add a keyword, and you're good to go. Repeat with other goggles.
