Hi Myriam. I don’t think you are overlooking anything. There is no built in capability to do that in Gravity Forms. It’s possible that Gravity Wiz Populate Anything could do that:
I will contact them and see if they can add any information to your topic here. Thank you for the question.
As Chris mentioned, this should be possible with GP Populate Anything. With GP Populate Anything, you’ll create a helper form, with entries that will be the possible combinations of product choices and options and those entries will be used to populate the Product and Options fields on the main form.
Also, you can use GP Conditional Pricing to setup different price for each Choice + Option combination. Please get in touch with us, so we can assist you further and closely to get started with this solution.