We are just users here, like you.
We users do not know anymore than you.
The new iPad Pros just got introduced and launched yesterday!
The fact that Apple is offering increased internal storage sizes up to 1 TB usually means that Apple is not going to let external storage drives direct connect to use with iPads.
If this worked, everyone would purchase base storage iPad Pro models and just connect up large capacity external storage drives. This hasn't happen yet with iPads. No need to believe this has changed any with the new iPad Pro, bjt we all simply won’t know this for sure until actual units are in the hands of users and Apple reviewers.
The new iPad Pros are not even shipping yet, so no users here are going to be able to tell you anything than what has been shown/announced in the product launch keynote.