For a product like Google pay that has likely a success metric of Transaction volume or number of transactions or amount per transaction, budgeting features may be counter-intuitive because the feature will likely impact the core metrics. But, Google usually takes a noble approach in its products. With that, I am thinking that it wants to provide a user with deeper insights into spent and budget for personal events. So, with this Google pay is likely improving the "engagement" with the app. Engagement here is defined as opening the app. Given the nature of the product, it is not a daily usage product but likely a weekly or monthly usage product. So, the success metric is an increase in WAU or MAU. By engaging more with the app, users will likely use Google Pay more paying for services (increase in transaction volume). The trade-off is that it can reduce the transaction volume if users get more conscious of spending. A/B test is the way to go.
Below are some customer needs:
1. As someone who wants to control my spending, I would like to see where I am spending the most (restaurants, subscriptions..)
2. As someone who wants to control my spending, I would like to be informed when my next subscriptions are going to get charged
3. As someone who wants to budget for some personal event (wedding, house purchase), I want to see how much is my spent overall and how will it take to save up the money for the personal event
4. As someone who wants needs social validation I would like to see how much I spend compared to other users like myself (demographics, net worth, goals..)
Prioritize the use cases based on constraints - i) dev resources ii) value of the feature that will drive the metric for success iii) confidence level in the feature. Based on the value I feel like 3) is the best use case. 1) is something that users can get from credit cards. 2) is a smaller use as not everyone has subscription services 4) I am ranking personal motivation for budgeting than social validation.
The use case I going to prioritize is users setting a target for budget and achieve their budget goals by analyzing the spent and income.