It's always worth asking the question, but also always doubtful that anyone who does know of a niche product, will in fact give up the information. It's just getting harder and harder to develop a niche market these days, stacks of research, test marketing ..... and then if you are fortunate enough to hit on a market, it doesn't remain a silent market for long before you have everyone else wanting a slice.
About the only half reliable niche markets left are those where people have access to products that have strong limitations to others getting hold of them. If you can find a product that does have a market, but strictly limited distribution, then you can be on to something, but the moment the product is easily sourced, you can find yourself being the one to do all the ground work to develop the market and then everyone else will piggy back in off your work as soon as they get a sniff of it.
Not great news, I know lol, but look for products with limited distribution opportunities, that's where I think the safest new niche markets lay.