I’m glad you are asking this question because this is exactly the right mindset you should have in a young Product Marketing org to avoid becoming solely a GTM service function.
The path to this is through a mixture of education and showing value to the Product team. Something you should find out is why the Product Marketing team was created and who was the driver behind the creation. If the momentum came from outside of the Product team, the PMs likely won’t know how to work with Product Marketing and this will be an opportunity for you to educate and bring the full scope of what you can do to the table.
If the momentum came from the Product team, you need to understand their definition and expectations for Product Marketing. If it doesn’t align with yours, understand where the gaps are and how you can work to close them over time.
One other thing to keep in mind - I hear a lot that the path to showing value to Product Managers is through customer insights. However keep in mind that most PMs are already gathering customer insights. Usually it’s on a much smaller and perhaps disjointed scale. For example, they’ll talk to five customers in-depth about a particular feature and the notes live somewhere in their drive vs. available for other PMs to consume. So a quick way to add value is to gather, centralize, and make searchable customer findings PMs have collected over time as well as to conduct customer research at scale that can eventually be benchmarked.