If someone identifies a niche that they're interested in, later signs a confidentiality agreement to review an acquisition target in that niche, makes an offer that's rejected, realizes that this niche might not actually be that difficult to build in, and attempts to start their own business in the space, is that indisputably impropriety and in violation of the confidentiality agreement?

How binding/defensible are confidentiality agreements in the US, especially (1) given individuals are often looking at many deals in the same space, and (2) in cases where there is no real IP/moat?