You can sign up for a StraitsX account from anywhere outside Singapore and Indonesia. Just go to this link to create an international account.
Remember, you'll still need to provide a valid proof of address from your current country. You can use documents like bank statements, utility bills, government letters, or phone bills from the last 3 months. If your documents are in another language, translate them into English and get them notarized. This step is important to make sure your documents are authentic for your StraitsX account's security and compliance.