The program will allow a small number of participating developers, starting with Spotify, to offer an additional third-party billing option next to Google Play’s own billing system in their apps. While Google already offers a similar system in South Korea following the arrival of new legislation requiring it, this will be the first time it will test the system in global markets.
Of note, Google said they will still be taking a cut of transactions, although they have not disclosed what that cut is. I would suspect it is less than the 27%, but we don't know for sure. I would speculate that this is truly a trial run and the rate today may not be what they go with if they release this widely to all developers.
I hope this goes well and both parties find this to be an improvement over today's single payment option.
As I suggested in 2020 and reiterated last month, I really think Apple should be working on an official way to take third party payments in apps. And if Apple insists on getting their 15-27% cut of each transaction, this would make it much easier for them to cut invoices for merchants on their platform since they won't need that merchant to provide an invoice for what needs to be billed, which is how their current proposal in the Netherlands works.