Super valuable. I made an attempt to implement something similar as a feature of a SaaS product I built, essentially taking a16z's list of metrics (like these),

Super valuable. I made an attempt to implement something similar as a feature of a SaaS product I built, essentially taking a16z's list of metrics (like these), then building data features into the product that produced them. Generalizing it like this is way better. A tool like this with an API would let founders and developers instrument their products with these metrics from the beginning. Even the list of user stories for the metrics features, "as a PM I would like to see the ARR/DAU/MAU etc, change over time" would be valuable. This clarity could really advance a lot of early stage companies and save them runway time.