If the business idea revolves around an app, you should have a look at App Annie. It's a great source of data and will allow you to see what's trending in your industry both on the App Store and the Play Store.
If you have a little bit of budget, you could also conduct your own market research using Google Consumer Surveys. It's very easy to use, and flexible enough that you don't have to spend thousands if you're happy with a smaller sample.
On top of checking out these other recommended resources, I would recommend hiring someone on Upwork. Be detailed about what you are looking for, good places to look, and how to organize it all. Good luck!