Ask HN: Pre-Seed Investment Calculation

Imagine there's a 1.5 trillion annually Total Addressable Market - TAM in the AECO (built environment) industry worldwide which there are few players in the market with infant solutions (for instance the bigger one is a series D startup with $350 million total investment) and your solution in the pre-seed stage is better and have the potential to become a unicorn in short time 1-3 years. How do you calculate your value? And how much should request from the investor in the pre-seed stage? and why?