For Windows a workaround using a UI from a NuGet package can be found in this article: How-To: OAuth2.0 Authentication in NET MAUI using Personal Cloud Providers. Its a bit tricky to get working.

For my purposes (to circumvent the need for a client secret that aren't safe in a native app), I ended up going a different route using a temporary local http server. See this article I made that works with windows and android: .NET MAUI Google Drive OAuth on Windows and Android