How to connect to sharepoint using pnp in Azure Automation Runbook with Managed Identity?

[SP-lbe]

Maybe it is allready answered somewhere, but this far i didn't find it. Maye I am just stubborn and it cannot be achieved at the moment using the connect-pnponline command...
What I am trying to achieve is to run a pnp script in en Azure Automation Runbook with an Azure Automation Account which has both 'Run as' as well as just activated Managed Identity. When I created Run as was pretty much the only option, but now Managed Identity seems the most secure way to go.
With the script I stored in the Runbook I want to provision Team sites from scratch, so I need to connect at the tenant level tenant-admin.sharepoint.com that I know. However when I try the method using client ID and client secret it doesn't work, saying I need an access token.
What is the best code to connect to pnp-online? I have a registered app in place using the Register-PnPManagementShellAccess but that works only for connect-pnponline with -userweblogin or -interactive.
Would greatly appreciate any pointers to the right direction. Preferably an example or code snippet but anything will do :-)

Thank you in advance!