I think you can only apply once for all countries https://merch.amazon.com/landing

I was declined nearly immediately and they never even looked at what I do. I sell on Etsy and I don't understand how they assess someone in a few minutes. I have seen real rubbish sold on Merch (and some copyright infringements), therefore it has nothing to do with the quality of one's work

Now I get this message: "We appreciate your interest, but your account request has been declined. We thank you for taking the time to introduce yourself to us and encourage you to check out selling options on Amazon.". I read somewhere that if you are rejected, you are banned for life.