@Aran Billen,Thanks for posting in Q&A.
From your description, I know you want to block USB drives but allow USB Mouse & Keyboard.
Based on my researching, we can use Administrative Templates in Microsoft Intune to restrict USB devices and allow specific some USB devices.
Here is a link about how to configure USB restriction policy.
https://learn.microsoft.com/en-us/mem/intune/configuration/administrative-templates-restrict-usb
Please try above information and if there is any update, feel free to let me know.
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