Headless C# OAuth Token Retriever

I need a small C# console application that signs in to a generic web service protected by oAuth 2.0, fetches the access token, and prints or returns it for downstream use. Everything has to run head-less: no Selenium, no hidden browser windows—just direct HTTP calls through HttpClient (or RestSharp if you prefer).

Login method: username + password only. For my own Microsoft-based test account an MFA push may appear; I will approve that manually on the authenticator, so the program only needs to wait and continue once the provider finishes the flow. For the production account there is no MFA, so the same username/password path covers both scenarios.

Key requirements
• Pure console app targeting .NET 6 or later.
• Uses the proper oAuth 2.0 flow to exchange credentials for an access token.
• No embedded browser or GUI—strictly API calls.
• Single configurable account; no multi-user switching needed.
• Clear, well-commented code plus a short README with build/run steps.
• Final output should expose the raw access_token (plain text or JSON) so I can pipe it into other scripts.

If you have previous experience with headless oAuth integrations and can turn this around quickly, let’s get started.