What metrics would you track if we are strategizing an increase in sales of Google's wireless headset?

Focus on identifying both quantitative and qualitative metrics that directly relate to sales performance and customer engagement for the wireless headset. Consider metrics such as sales volume, revenue growth, market share, and customer acquisition cost. Additionally, think about user satisfaction metrics like Net Promoter Score (NPS) and customer reviews, as well as engagement metrics like usage frequency and return rates. Be prepared to explain why each metric is relevant to the sales strategy and how it can inform decision-making.