Hi Ben44 ,
Here are the steps to use a Service Principal with SharePoint:
Create a Service Principal: Service Principals are created as an app registration in the Azure portal or by using PowerShell. When creating your Service Principal, be sure to copy and save separately the app name, application (client) ID, directory (tenant) ID, and client secret.
Create a Microsoft Entra security group: By default, service principals have access to any tenant settings they’re enabled for. To restrict service principal access to specific tenant settings, you can allow access to specific security groups.
Enable Service Principals: Before you can start using service principals in Power BI, an admin must enable service principal access in the Power BI Admin portal.
After the above steps, you can add the service principal to your workspace.
For more you may refer to：
Best regards.
Community Support Team_Caitlyn