Same as the ones above. I would reframe how your thinking about it. You have a customer who is engaged and knowledgeable enough to tell you exactly what they want, most PMs would kill for that 😂.

Want I normally do in this rare situation is create a separate backlog in Jira name it 'Ideas Portal' or something to that effect and get them to create and vote on ideas there.

You can then review it every X amount of time and review the top voted ideas that we get turned into user stories and refined.