Often Founders, Product Leaders and PMs struggle to define what are the important things to measure.
In these instances, I like to take them out of the Tactical mindset (what do I measure??) and back to the high-level Strategic discussion (why are we doing this?).

Why are we doing this? What does success look like? … both for you and for the customer. Ask those questions first and then work towards a quantifiable criteria which can be measured.

What Success looks like → How does the Customer achieve that → So, how do I measure that.

Sometimes that’s as simple as looking at DAUs but in most other cases we need a measurement for a specific journey with a more particular KPI.

Abstracting the problem helps to get better clarity.