I beg you, if you are a developer of an open source app or program - add screenshots of your app to the README file. When looking for the perfect app, I had to install dozens of them just to see what the user interface looked like and whether it suits me. This will allow users to decide if the app they choose will suit them… Please, don’t think about it, just do it…
I feel like maybe you don’t know what a headless component library is. A cli has a head – the terminal. Headless applications, by definition, have no visual portion. For instance, a headless browser is a browser where the web page renders in-memory, but never displays any content. A headless component library, then, is one where the implementor doesn’t provide anything visual, only behavior. For web dev, is very helpful – the library implementator writes all the js, but the css and html (the “head”) are left to the user for use. The best headless component libraries, then have nothing to screenshot without the user supplying some implementation.