OAuth2 with external system browser

I currently have an electron app that authenticates the user by displaying a third-party login page in the embedded browser. The login page also give the option of a Google sign-in. Due to Google dropping Sign-in support for embedded browsers, I’m trying to move that process to an external browser.

Is there a guide/tutorial anywhere to outline how this achieve this using an authorization code grant approach? It seems that information on how to facilitate this is scarce.