Yes. LibWeb and LibJS were written for the SerenityOS. As mentioned in the article, some work was done to make them buildable and usable on Linux in a headless

Yes. LibWeb and LibJS were written for the SerenityOS. As mentioned in the article, some work was done to make them buildable and usable on Linux in a headless environment. The Ladybird project is then taking that work and adding a Qt GUI on top of it.