They all use Discord and/or Snapchat here in Australia. No one I've every asked about this cares about Android vs iPhone. No one.
No one apart from the Parents uses the built in messaging and SMS.
But then the Parent groups all use Facebook Messenger for most group comms.
The whole green / blue bubble thing is either over played by the Press or purley a US Phenomenon.
But given the marketshare of the iPhone with teenagers in the US, it seems it's possibly less of an issue its made out to be due to the fact that most people have iPhones anyway!