[UPDATE] YouTube Music has just launched in Poland, Czechia, Romania, Hungary, Bulgaria, North Macedonia, and Cyprus. YouTube Music and YouTube Premium are now available in 50 countries, 10 times more then when it re-launched a year ago.
The services previously launched in the United States, Argentina, Australia, Austria, Belgium, Bolivia, Brazil, Canada, Chile, Colombia, Costa Rica, Denmark, Dominican Republic, Ecuador, El Salvador, Finland, France, Germany, Guatemala, Honduras, India, Ireland, Italy, Japan, Luxembourg, Mexico, Netherlands, New Zealand, Nicaragua, Norway, Panama, Paraguay, Peru, Portugal, Russia, South Africa, South Korea, Spain, Sweden, Switzerland, Ukraine, the United Kingdom, and Uruguay.