If it was in google IO, it will be some consumer use case probably? Althought there are a lot of commercial use cases of this technology. For example, you can train a simple classifier on top of pose which will help you record time spent on different types of activities which is useful in measuring productivity.

Just a fun dance recognition app to show off ML.

I can think of a couple of use cases, none of them particularly useful though. Imagine you had the pose data for the image and the pose data of someone else, even an imaginary someone else thanks to GaNs.

Dance Dance Revolution, but without the sensor mat?

https://en.wikipedia.org/wiki/Dance_Dance_Revolution