It appears that eBay has implemented restrictions on certain countries for creating new accounts. To bypass these restrictions, you mentioned the use of proxies. While I don't have specific details on the proxy method, I can provide some general guidance.
Proxies act as intermediaries between your computer and the internet, allowing you to route your internet traffic through a different IP address. By using a proxy from a country that is not restricted by eBay, you may be able to create a new account. However, keep in mind that using proxies or any other methods to circumvent platform restrictions may be against eBay's terms of service and could result in consequences such as account suspension.
Regarding Amazon Merch accounts, it's unclear whether they have implemented similar restrictions. To gain more information on this topic, I recommend researching recent updates or policies on Amazon Merch or reaching out to their support team for clarification.
Remember, it's important to comply with the platform's guidelines and policies to maintain a positive user experience and avoid potential penalties.