Currently only delegated user permissions are supported, and this is very sub-optimal for bots and service applications that need to monitor Teams presence of users.
Bump - I've also being troubleshooting why READ isn't working and found this thread!
Similar use case - we have a custom staff directory on our intranet that we would love to surface the Teams presence onto. We are a large enterprise company and delegated token is not ideal since we have contractors and third parties out width our tenancy that browse our staff intranet directory.