How To Sell A Digital Product With Dynamic Content

We have a scenario where we have created a page with a code block that contains some input fields, some dynamic content and a button that produces a pdf containing product content. We want to sell this pdf product but we are not sure what options are available to do this in Squarespace. Ideally one user (a coach) could purchase access to the page, use it as many times as possible during a time period and give access to others (coachees) to use it. Are there any ways that we could do this?

All of our current products are static resources that we can sell from the Shop and it doesn't seem like you can have products that are customizable by users when they buy a product.

The other thought we had is to use a members only area and have the page in there. A user could pay for a months access and use the page to produce as many customized pdfs as they like. However to facilitate multiple related people (coach/coachees) they would all need to use the same account. A scenario like the coach creating a generic account/password and paying the subscription and then sharing that account to their coachees to access the product page to produce and save the pdf. The sharing of the one account login details isn't really ideal.

Are there any other options available?