Hi Andrew,
It is not currently possible to print a copy of the survey to a file (Word, PDF or image format) directly from within the app before submitting. We do have an enhancement request for this feature and I have updated it with your comments.
As you mention there could be others ways to do this by formatting the json, however I am not aware of any other users that have successfully done so on the device before submission.
This may not help, but not sure if you are aware that we are currently working on a new feature to support Webhooks. While the Webhook will only be sent on submission, not before, we do see scenarios where it could be used to enable printing on the device of a report (Word/PDF etc), as after submitting the record, the report gets generated online, and then gets sent back to the user via email as an attachment. Webhooks is currently in beta and will be released with further improvements in a coming release and we are also making further improvements to the Reporting beta functionality available on the website. You can find our more information on both of these via the Blogs and Early Adopter Community.
Phil.