What metric should Product Managers primarily focus on to help guide the evolution of the...

Outcome metrics are the metrics that measure the impact and value of a product on the customers and the business. Outcome metrics help product managers to guide the evolution of the products by focusing on the desired outcomes and benefits, rather than the outputs and features. Outcome metrics also help product managers to validate the assumptions and hypotheses behind the product strategy, and to iterate and improve the product based on customer feedback and data.

References:

Outcome Metrics - Scaled Agile Framework

5 Essential Metrics for Product Managers

Output vs. Outcome Metrics: What’s the Difference? | ProductPlan