To work in this exchange, you must be authenticated, so if you are looking for an exchange with which to start trading immediately, I do not recommend poloniex. Of course, this exchange does not only serve countries that are under US sanctions, and with the exception of a few countries, other countries can operate in poloniex. Of course, they still have to do authentication, and this can be time consuming. Also, if your documents are not in Latin, you will have to translate them through official translation centers and then submit, which will be very time consuming and you will probably have to pay a fee for translating the documents.