This is one of the easiest pets to get. I joined a pre-made group ( you need 5+ people) and all you do is pet the surrounding Larion cubs at the same time and Courage spawns. Here’s a link to the details. One caveat, someone states that a medium sized Courage lion needs to be flying around Nemea for Courage to spawn. This is not true.
World of Warcraft: Shadowlands - How to Get the Courage Battle Pet (gamerant.com)