You could also check what people are complaining about / asking help for in relevant subreddits and see if you can build a product around that.
I ask because I often see the advice that people should look in the Shopify/Hubspot app stores for paid apps with lots of users/ratings and a low score, and while this sounds good, I've found very, very few apps that actually match these criteria. Typically a low score indicates a complaint that is outside of the technical scope that the app owners could address, and ends up being a weak signal imo.
I don’t do what you mentioned (ie. look for paid apps with lots of ratings & a low score), I look for any app with at least one 1 star or 2 star reviews and I also look for any problem (doesn’t have to be related to an app) in reddit or any forum.
To be fair, it’s quite a numbers game to dig for useful problems or insights.
A related video about the process is Amy Hoy’s Sales Safari: https://youtu.be/67JVkG4dpj4
So it doesn't matter if the app overall has a good rating, you're just looking for the signal that some subset of users isn't getting their needs met?
How do you trust a single 1 star review as validation?