A web-based log viewer app is a beginner-friendly project that helps you to learn how to work with file-systems and string manipulations. It should have different types of reports based on the log type (error, info, critical, exception, etc.), date, and time, and also the user should be able to search through the log history. If you want to make it more challenging for yourself, try to make it realtime.
Something like this but first, a web-app and second support more languages and frameworks.
Create an image EXIF viewer/parser. This idea is for beginners or mid-level programmers who want to understand how to work with images. If you are keen to learn more, you can make a web app to parse/edit/delete the EXIF data for a specific image.
I've never read a scientific paper or even a scientific page on Wikipedia because these kinds of articles and papers are written for advanced English users.
As a non-native English speaker, I wish there were a web-extension or service that helped me understand scientific texts by simplifying them.
This can help children, non-native speakers, or people who are learning English.
Take a look at: https://simple.wikipedia.org/wiki/String_theory.
Reddit has millions of users outside the United States, and almost all of them are sick of US politics' posts on the front page. I wish there were a web-extension that removed these kinds of posts for me.
Or you can take one step further and replace the post with something funny or some dog's/cat's picture. I believe everyone will be happier.