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…
For a lot of open source at the moment the root level readme is fundamentally the homepage too. It absolutely should include screenshots, maybe even a gif. If your software has a GUI or TUI it should follow that a concise visual will do more to explain it’s usage than a text document