In college I had a class focused on Ethical Web Development. It's a large part of why I have a statically generated website in the first place. As part of that class we also learned how to make Progressive Web Apps using Vanilla Javascript. These are very responsive web-pages that can also be downloaded like apps on a phone.
Below are the different JavaScript projects I've worked on.
Weather Progressive Web App
A simple Weather PWA that uses OpenWeather's API to fetch data.
Source-code: Gitlab, ProjectIdea9