First off, congrats on the launch! Construction is a tough market to build in. My personal view after being in it a for a few years is that there is no shortage of MVPs. In fact there is an MVP for every problem at every level (or at least it feels that way) but construction is /vast/ and the rough edges that seem juicy at first, in practice are optimizations rather than bottlenecks for constructors.

I hope you succeed because it would be great to have a standard API for this data, but I would advise on one of two directions: become the standard by being close to 100% accurate at finding symbols (one symbol doesn't seem to cut it in our testing) or make a great, comprehensive workflow for a small subset of the market and become standard that way.

In both cases, you cannot do a broad 'market test', you need to spend many hours with a specific sub-set of users in construction.

Disclaimer: I'm a co-founder of Provision.