Good question. We have SBA defaults data on a very granular NAICS code level, but GDP data on a very coarse level - which cannot be decomposed. The downside is that to do this analysis properly you need to map all the granular SBA data into coarser groupings.

So HVAC, electrical, plumbing etc are all going to fall under construction

From a top down perspective there is some triangulation you can do: "hot" industries are that way for a reason - look for the underlying reason and think about how that applies to other industries; what industries do you know or have experience in; where have there been deals in the size you're after recently (resources like deal stats are good for this). Then bottom-up research to build out a rationale. AI is certainly useful with this, but nothing beats going through the hard thinking and research yourself, complimented by research tools available, AI to help accelerate understanding, and conversations to validate.