Why was that?
Because the first 9 months it was a volunteer project fixing the air quality problem of the school our kids go to. During the so called "burning season" the school did not know if the air purifiers in the classrooms can keep up.
So we developed a solution tackling exactly this problem spending many many days on campus and talking to teachers, administration, parents and operations.
So instead of starting with an IDEA of a product/service, we started focusing 100% on fixing an existing massive PROBLEM on the ground.
Another thing that worked for us was to early on offer an open-source version of our air quality monitor [1] that allowed us to see what adjustments the community came up with - as in many cases these adjustments made the monitor fit better to problems we might not have been aware of. So basically a kind of community driven market fit.