Other Intune-related topics, including unsupported scenarios and platform-specific behaviors
@Go believe Based on my understanding, it is needed to create two conditional access policies to make it.
Please filter the target devices in "include filtered devices in policy" and select grant access in the first conditional access policy. It will make the target devices can access the cloud app.
Then filter the target devices in "Exclude filtered devices in policy" and select block access in the second conditional access policy. It will block other devices to access the cloud app.
Hope it will help