RenzoHannaford
Why is that so surprising?
In India, nothing products are not sold directly from nothing website, they are sold on a third party marketplace which is similar to amazon. You can exchange any brand phone for any brand of purchase. This is the case with all the other marketplaces in India, including amazon India.
Also, other brands which sell phones directly from their site also have the option to exchange. There are even bonuses and additional discounts when you exchange your phone.