Ask HN: How to identify potential projects that have real demand and interest?

When browsing GitHub issues and discussions of large libraries and frameworks, it’s often easy to spot topics that attract a lot of attention and go on for months or even years. These are usually complex bugs, missing features, or controversial design decisions and limitations that frustrate a large number of users. Also, there are the obvious problems that every user encounters right after they start using the library.

It’s clear that among such topics there’s some potential, if you can offer a solid solution to one of those shortcomings in any form, the market has already been "researched" to some extent. That solution can take many forms: a patch, a fork, or an entirely new library or project. It’s also great material for quality blog posts and YouTube tutorials.

This is just one example of thinking in that direction, but there are certainly many more. When someone decides to invest time and energy into side projects, they definitely shouldn’t do it blindly, without any indication of potential demand for the solution they’re building, the market needs to be tested.

So how can this be researched systematically and empirically, in order to have a fairly reliable idea of how popular the finished project might become? Is there some kind of routine checklist for that?