I'd suggest dont split the KPIs. Here is why
Product Management and Product Marketing are two different ways to accomplish the same outcomes. The difference is one is in product and the other is outside of product but both the experiences are touching the same customer and driving the same north star outcomes.
But in some cases that may not be possible either because of the org structure or just how your company functions. If that is the case I would suggest to map out both the in product and out of product journeys on a unified customer timeline and then go through identifying KPIs, dependent KPIs and counter metrics. Whether the org structure permits or not, Product Management and Product Marketing is dependent on each other, what one does will impact the other one and vice versa.