How to Answer the Question 'What Would You Build?' in a PM Interview

The question 'What would you build?' is commonly asked in product management interviews to assess a candidate's ability to innovate and raise the bar of the company. The interviewer is looking for one good idea, and typically prompts the candidate to pick any app on their phone and propose a new feature as if they were the PM of that app. The wrong answer would be a vague idea without considering the company's goals and metrics. The candidate is encouraged to be familiar with the company's goals, KPIs, and metrics, and can use the whiteboard to demonstrate their response.