Great question, difficult to answer. The financial metrics and KPIs that we look for ahead of a new investment is specific to the company and the company's stage.
Generally speaking, a very early stage company should demonstrate a clear understanding of an opportunity to (a) provide value to an identified user group and (b) a plan to monetize that value efficiently. Variable (a) is the product and (b) is the business model.
For example, "BTC hodlers in Southeast Asia need X. We believe we can acquire these users for $Y/user and charge $Z/user/yr."
As a company matures, these hypotheses are tested and user feedback can be applied to evolve the product and marketing. This should accelerate growth and drive a company's financial health and overall progress. Metrics that prove such an evolution are evaluated at that stage.