I understand that this is a very deep and technically complex improvement. I am not familiar with the internal mechanics of Condenser and a button that responds with an action to a purchase should communicate the public part (customer) with the private part (server) to ensure the privacy.

In my opinion the system can start working with 2 options to the purchase:

When purchase sucess:
a) Reveal digital product download link (only to the user who buys)
b) Make a transaction (Steem/SBD/SMT)