Rest Endpoints for EXO Commandlets

Howdy y'all, 

I'm trying to write some dashboards that involve using OAuth to authenticate on behalf of the users. Normally, this is pretty trivial via the Graph API. However, I don't see endpoints to access mailbox permissions (especially members on shared mailboxes) via Graph. I read that the EXO commandlets in PowerShell are rest-based, but they themselves don't support OAuth tokens for authentication. Are those rest endpoints exposed so I can hit them externally, or any other way that I can access them using tokens for authentication?

Thanks!

Will