Apple admits that iMessage for Android was killed to keep its walled garden - Android Police

As early as 2013, Apple decided not to develop a version of iMessage for the Android OS.

Phil Schiller, an Apple executive in charge of the App Store, agreed that Apple should not offer iMessage on Android devices.

In 2016, when a former Apple employee commented that “the #1 most difficult [reason] to leave the Apple universe app is iMessage.

The statements cite Eddy Cue (SVP of Internet Software and Services) acknowledging Apple was capable of developing a version of iMessage for Android as early as 2013.

An additional comment by another Apple employee emphasizes that iMessage is the biggest factor in keeping people in Apple's ecosystem and refers to it as "serious lock-in."

Of course, there's no technical limitation preventing Apple from developing iMessage for Android, and most people already assume this has been a strategic decision

Apple has never commented on whether it plans to build a version of iMessage for Android, but with these statements in the open, it's easy to understand why there has been radio silence on the subject