BlendShapeController timeline track - pose & animate blendshapes on Unity's Timeline
Found this on the Unity forum: https://answers.unity.com/questions/1566416/how-to-read-the-track-binding-from-a-timeline-beha.html
Take zero credit for the work, it's just super cool.
Simply clone / copy into a project and it should 'just work' - tested in 2018.4LTS