Hi Javier,
Thanks for asking this question. It’s indeed possible by creating an Automation workflow.
You can build a workflow by following this tutorial :
Once the workflow is built, you can delete the action “Send a mail”, and replace it with the action “Add a contact in a list”.
In the point of entry “A contact has generated an event ‘order_completed’”, you can click on the option “Add conditions to the selected JS event”.
Then, you may select the “Tracks events” option, select “items”. In the next field, you would need to type “name”.
In the last field, you can put the name of your product.
Once done, you can enable the workflow. A contact who purchases a specific product will be added in a list.
Please let me know if I can help you on anything.
Best Regards,
Alexis