"Over the coming months, Spotify will work with Google’s product and engineering teams to build this new experience" It's so absolutely bizarre to announce something at this stage. I wonder what is prompting it.
Instead of building something and then cancelling it later when it doesn't gain traction to get their PR win, they decide to cash in on the PR win upfront with a big partnership announcement, then cancel the product before building it if it doesn't gain sufficient traction, thus saving on engineering costs and streamlining the typical Google technical offering lifecycle.
Behind the scenes, Google usually gives the partnering company some pretty nice discounts. Usually no one does any engineering until someone else sees the PR and also wants in on this "exciting new feature" and they're the one actually beta testing the product that they thought the announced companies already used.