What framework do you use to figure out the right additional products?
Assuming your question is on how to prioritize the right set of features, here is my answer:
First step is to understand customer scenarios/workflows and associated pain-points and needs. Combine that with business opportunity of that investment, also having a close eye on the market and compete landscape. Finally, use rigorous prioritization to focus on highest ROI - take into account both customer/business value as well as associated cost to deliver. This is no different from a typical Product team. A key focus on platform team should be to invest in durable, long-lasting capabilities that will benefit many customer as opposed to focusing on short-term wins for a select set of customers (this can result in custom solutions that become hard to generalize in future).
At Carta, we follow this framework to invent new products and then iteratively transform them into core competencies:
Test & Learn: A test is a non-permanent addition to our product designed to prove or disprove a specific hypothesis. Here, we emphasize speed and innovation with sufficient UX.
Feature MVP: A Feature MVP is a feature in which we have high confidence of good performance in our product. It aims to achieve enough user engagement to inform how we should iterate on the product.
Feature Iteration: This stage involves the further development of an existing feature to enhance ROI. The focus here is on improving usability and scalability.
Platform Capability: This is about creating a reusable and composable infrastructure that empowers other product teams. At this stage, we focus on codifying patterns into APIs to enable other teams to build on top.