What is Your thought on shiping prototype stage products to early backer as a way of getting user feedback. Even if product is not yet certified, with the promi

What is Your thought on shiping prototype stage products to early backer as a way of getting user feedback. Even if product is not yet certified, with the promise that you will ship them the finished product? This way you are not selling the product you shipped them, so I'm not sure what are regulations regarding this strategy. The product would be clearly labeled as prototype version and not fit for end use. Bonus points for complexity: The product is intended for children age 6+.