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Please, download the latest CEF4Delphi from GitHub.
It has a new OAuth2Tester demo that might be what you need. Read the code comments in that demo because you will need to create some "credentials" in the "Google API Console" to see some results.
That demo uses the system browser to login. When the user has been identified it sends an "access token" used in the REST API requests.
I tried to use that token while navigating to youtube.com or google.com with TChromium but it was ignored by the server and it showed the contents as an unidentified user.
This can bypass simply by using UserAgent string similar to Chromium/Chrome/FireFox/Edge as I tested on CEF for QT, CEF4Delphi all successfully.
This test code on 6/5/2022 is SUCCESSFUL with the FMXTabbedOSRBrowser project. You can check for any Windows CEF4Delphi apps.