Hi,
There is no direct way to do that.
However, you can do that by using our integration with AcyMailing:
Create a product for your coupons.
Then, in AcyMailing, create a newsletter with a hikashop coupon tag.
Finally, create an auto filter (AcyMailing Enterprise) with a condition on your product and an action to send the newsletter and set it to be triggered when an order is confirmed.
That way, AcyMailing will generate a coupon code and send it in an email to the user once the user's order of the product in confirmed.
The limit is that you can only have one coupon per order. so you should limit the maximum number of products per order to one for that coupon product.