Ask HN: Where to find neglected niche market opportunities?

Hi, everyone. I am a new indie hacker trying to build my own businesses.

I follow some developers build in public in Twitter and pay attention to new products in product hunt. But I find many people just develop products which are fashion (like new AI tools) and attract others developers (like build in public). If the product doesn't aim to developers, building in public has little use.

I want to be more closer to customers and neglected niche market, instead of being close to technique and developers. Do you have any suggestions where to find them? Thanks so much