Consider adding the Open in Mobile View option for the OneDrive for Android app
Consider adding the same "Open in Mobile View" option/ability to the OneDrive for Android app as you have in the new Office app for Android. I was experimenting with viewing a Word document in my Personal Vault with the OneDrive app for Android and it's easier to read a Word app with the Office app for Android.
An alternate idea would be to allow the new Office app for Android to access your Personal Vault in OneDrive. The Office app lists documents stored in the Personal Vault but fails to open them, even if the Vault is unlocked.