How can I validate willingness to pay for a B2B SaaS for small architecture firms?

[Jerry_W]

I'm a solo founder developing a B2B SaaS tool for small architecture firms, and I'm in the early stages of market validation before committing to full-scale development. I've conducted about a dozen interviews with potential users, but the feedback is conflicting—some love the core concept, while others say they'd never pay for it. For other founders who have navigated this phase, what are the most effective methods for moving beyond anecdotal opinions to gather quantifiable validation? How do you design a minimum viable product or even a concierge MVP that truly tests willingness to pay, and what key metrics did you decide were non-negotiable before proceeding to build? I'm worried about building something nobody wants.