pipCallbacks.kt

private fun startPictureInPicture(): Boolean {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O && shouldStart) {
        enterPictureInPictureMode(
            PictureInPictureParams.Builder()
                .setAspectRatio(…) // This has lower and upper limitations
                .build()
        )
        return true
    }
    return false
}

override fun onUserLeaveHint() {
    super.onUserLeaveHint()
    startPictureInPicture()
}

override fun onBackPressed() {
    if (!startPictureInPicture()) {
        super.onBackPressed() // Only execute if PiP is not started
    }
}