Appeal to the nobler motive
A business usually has two reasons for doing a thing: one that sounds good and a real one. The product manager will think of the real reason. Their job is about finding monetizable market opportunities. Business results matter and acquiring new customers and increasing average revenue per user is part of the monetization equation.
But all of us, being idealists at heart, like to think of motives that sound good. So, in order to make it sound appealing, we talk in terms of what customers want. There is an approach called "working backwards" that is widely used at Amazon. Work backwards from the customer, rather than starting with an idea for a product and trying to bolt customers onto it. Because value springs out of what customers fundamentally desire.
The only way to influence product teams is to talk in terms of the nobler motive. A discourse centered around the customer problem, how the solutions will solve it should eliminate the lack of conviction among key stakeholders.
Your primary role is to create monetizable customer value. Appeal to the nobler motive to get your team onboard.