The Product Owner is a rolle within Scrum, so The Scrum Guide (https://scrumguides.org/scrum-guide.html#team-po) defines the boundries of an Product Owner. Nothing more or less.
If we talk about responsibility most people think about Job Design (https://de.slideshare.net/RaphaelBossek/product-management-job-design). In this discipline we have to talk about Software Product Management (SPM) first.
I like the ISPMA overview where the common jobs of an Product Owner are in the column “Product Planning” and “Development”.
As shown by ISPMA there are areas of participaction, core Software Product Manager (SPM) activities and orchestration.
Don McGreal and Ralph Jocham are talking in their book “The professional product owner” (https://www.infoq.com/articles/book-review-professional-product-owner/) about an existing gap in direction of Product Strategy and Strategic Management. But this is only the left side of the picture.
Second. As Product Manager you can not leave Marketing, Sales/Distribution nor Service/Support out of your focus.
Marketing is the science and art of exploring, creating, and delivering value to satisfy the needs of a target market at a profit. Marketing identifies unfulfilled needs and desires. It defines, measures and quantifies the size of the identified market and the profit potential. It pinpoints which segments the company is capable of serving best and it designs and promotes the appropriate products and services. (https://www.kotlermarketing.com/phil_questions.shtml)
Marketing defines for example the customer problmes and their business value. It’s Product Owner’s responsibility for maximizing the value of the product resulting from work of the Development Team. Zalman, Peter (2020): Backlog Prioritization (https://medium.com/enterprise-ux/backlog-prioritization-59baa3d9d75e) explaines very well how it’s done.
As mentioned by many Venn diagrams out there, the Product Owner may focus on the user not the customer with the “Development” and “UX” experts to optimise the outcome.
At the end it is not an question of responsibility, agility nor waterfall but accountability, as described by Mercier, Devin (2018): 6 ways managers can increase team accountability (https://medium.com/pathlight/6-ways-to-increase-your-teams-accountability-91f2308faa95), and your skills to master growth — as you mentioned the outcome.
Further readings:
Eriksson, Martin (2015): The History and Evolution of Product Management. http://www.mindtheproduct.com/2015/10/history-evolution-product-management/
Cagan, Marty (2012): The Product Manager Contribution. https://svpg.com/the-product-manager-contribution/
Adams, Paul (2017): Great PMs don’t spend their time on solutions. https://intercom.com/blog/great-product-managers-dont-spend-time-on-solutions
Tarabi, Nima (2020): Aligning ‘product management’ and ‘product marketing’ efforts. https://uxdesign.cc/aligning-product-management-and-product-marketing-efforts-8b48cbfa8a9a
product focus (Hg.): Product Activities Framework v4. https://www.productfocus.com/product-management-resources/product-activities-framework
Gnanasambandam, Chandra; Harrysson, Martin; Srivastava, Shivam; Srivathsan, Vaish (2018): The product management talent dilemma. https://www.mckinsey.com/industries/high-tech/our-insights/the-product-management-talent-dilemma
Cagan, Marty (2011): Developing Strong Product Managers. https://svpg.com/developing-strong-product-managers
Boström, Raoul (2018): The 10 best and worst Venn diagrams explaining product management. https://productcoalition.com/the-10-best-and-worst-venn-diagrams-explaining-product-management-f6006c82476c
