blinking_circle.xml

<?xml version="1.0" encoding="utf-8"?>
<animation-list xmlns:android="http://schemas.android.com/apk/res/android"
    android:oneshot="false">
    <item
        android:drawable="@color/transparent"
        android:duration="700" />
    <item
        android:drawable="@drawable/circle"
        android:duration="700" />
</animation-list>

circle.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval">
    <solid android:color="@color/purple_500" />
    <size
        android:width="8dp"
        android:height="8dp" />
</shape>