Choosy opens links in the right browser, so you can forget about the "default browser". When you click on a link Choosy will do the right thing, whether that's something simple (like using whatever browser is already running) or something complex (like prompting you to pick a browser, but only when you hold down the shift key and click on a link to google.com).
Updated on Nov 30 2020
Note: This version of Choosy requires macOS 10.15 (Catalina) or later. For earlier versions of macOS, try Choosy 2.1 instead.