The real problem is triage
Sellers on business marketplaces rarely complain about volume. They complain that the good enquiries are hard to find among the price checks, the traders comparing rates, the buyers three thousand kilometres away for whom freight makes you uncompetitive, and the students doing a project. The skill is not in generating interest, it is in sorting it quickly enough that the viable enquiries get a fast, professional response while the rest consume minutes rather than hours.
That framing changes the process design. You are not building a nurture funnel. You are building a sorting mechanism with a fast lane attached.