Opening Locked PAGES Document

I'm not aware of any recovery process for Pages documents.

FaceID may not help you. Recent Pages versions can save the password in your Keychain (where FaceID can retrieve it), but it had to be setup that way when the document was saved, and that password is only saved on the device it was created on (it isn't shared across devices). If you didn't save the password in your keychain then you'll need to recall what it was.

As a fallback, you can check your Keychain (look for a key whose kind is 'iWork Document')

The keychain is a secured, encrypted repository of key/account data. Ideally, when applications (such as Safari) want to save credentials (such as the username and password used on any given site), target save it into the keychain.

as such, what you should see when you look at the keychain (either via Keychain Access.app on Mac, or Settings -> passwords on iOS) is a list of sites and/or applications. Web sites should typically be listed by the web site name, and within the keychain is the username and passwords used within applications (such as Pages documents) are typically listed by application.

however, as I mentioned earlier, by default, Pages on stores document keys/passwords on the local keychain (I.e on the specific device itself), not in the shared keychain that is synched across devices connected to the same iCloud account. This means if you created the encrypted document on a Mac, your iPad would not have the key. You’d need to manually copy that key to the shared keychain, or read the password from there and retype it.

what I don’t know is where Pages on iOS stores it’s passwords since there is no obvious ‘local’ keychain on iOS, but I assume it’s in the same area.