So are you selling pre registered domains or one can order any available domain ?
Why are you selling in auto buy from selly ? There is no way you can instantly deliver the domain through selly platform as one has to provide you with the domain.
How does it work, you register the domain and transfer to buyers account or provide a code for the buyer to get it free after paying you the money?
No, you will order your own domain name using the code I will send you after purchase.
Let me know your preferred payment platform instead If you don't like selly.