Hello!
It´s possible to use App ID and a secret key to get a token to access Sharepoint online.
https://www.sharepointpals.com/post/how-to-generate-app-id-secret-key-to-access-sharepoint-online-through-console-application-using-access-token-part-1/
I don´t found this option in Microsoft Connector node. Maybe this could be an especific configuration of Sharepoint Online Connector node. Is this a viable upgrade to implement?
Regards.