@Anonymous , Based on my research, I find we need to turn on Full Keyboard Access when we want to control iPad with an external keyboard.
https://support.apple.com/en-sg/guide/ipad/ipad424a3e13/ipados
Note: Non-Microsoft link, just for the reference.
From your description, I know when we grant full accessibility, the files can open. I think Full Keyboard Access is a necessary step when we want to use external keyboard.
In Intune app protection policy, currently, there's only option to allow third party keyboard. In the setting description, it seems the Intune APP SDK instructs the OS to load keyboard extensions/ third party keyboards while company data is actively being used in the app. We can set it as allow to see if the external keyboard can work.
https://techcommunity.microsoft.com/t5/intune-customer-success/updated-known-issue-third-party-keyboards-are-not-blocked-in-ios/ba-p/339486
If there's any update, feel free to let u know.
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