https://www.theverge.com/circuitbreaker/2018/5/17/17365790/google-home-play-movies-library

Before today you could ask Google Home (and in turn, Google Assistant) to play shows on streaming services like Netflix and Hulu, but not with Google’s own Play Movies service.

All that changes today, now you can ask Google Home to assist your TV show or movie binge-watching without ever needing to link accounts — after all, you’re using Google Assistant to access another Google service, so everything is attached to your account. This applies to both rented and purchased movies or TV content, as well.