In a press release from Apple about the new software update for HomePod, it mentions all the new features that were added with iOS 12 for HomePod, but at the very bottom of the page it mentions
HomePod is available in Australia, Canada, France, Germany, the UK and US, and will be available in Mexico and Spain starting October 26. HomePod is available in white and space gray at an Apple retail price of $349 (US) from Apple Stores, apple.com, the Apple Store app and at select Apple Authorized Resellers.
Starting from the end of this month, on the 26th October the HomePod will be on sale in Spain and Mexico.
Source: Apple Newsroom
News via: MacRumors