Google Credential Provider for Windows® (GCPW) lets users sign in to Windows® devices with the Google Account they use for work. GCPW provides users with a single sign-on experience to Google services and all the security features available with their Google Account.
Google Takeout saves emails as .MBOX file format, which were used on Unix. MBOX files are still used with Mozilla Thunderbird, Microsoft Entourage, Qualcomm Eudora, Apple Mail...