The Product Owner is like an architect. The Product Owner must know something about everything.  The Product Owner is a generalist, not a specialist.  To succeed, a Product Owner coordinates a cadre of professionals including engineers, designers, developers, testers, regulators, auditors, and other specialists from many disciplines.  The interests of some of team members will likely conflict with the interests of others.  This conflict is expected.  The Product Owner must be able to assimilate information from each discipline to determine the best decisions that honor the needs of the stakeholders and maintain the integrity of the overall product.