WhatsApp based Quotation Generator

I'm looking for a Full Stack Developer to build the MVP of a SaaS application that enables tradesmen / small businesses to create simple quotations entirely through WhatsApp. The system should guide users through a conversational workflow, generate PDF quotations, store user profiles and quotation history, and include a simple web-based admin panel. The technology stack is open—I welcome recommendations on architecture, frameworks, and implementation. Please share your relevant experience, proposed approach, timeline, and fixed-price quote.