Because this is the way, Disney+ coming to smart displays
If you’ve got a Google Assistant smart display, Nest Home Hub, or another similar Google-ecosystem product, Disney+ is going to be available on it at some point shortly so you can put the kids in a room with an assistant screen and get some Moana playing on the small screen.

As with all things Google lately, you’ll get it when you get it. The announcement came today on the Google Blog and this is not a thing that you can force an update on. You’ll need to add your Disney+ account in assistant settings or the Home app, and if you don’t see an option to link it there, well, I wish you well while waiting.
[Google Blog]