Use MSAL mobile app authorization method to access other microsoft website such as microsoftstream

Question

Hi our company's mobile app is using Microsoft Active Directory for employee access management, the authorisation method we have implemented is MSAL and we have managed to get the access token to call Graph API.

However we also need to be able to access other Microsoft products/websites such as https://web.microsoftstream.com using in app webview, how could we achieve that without reauthorisation in the webview?

Thank you very much.