Here's the Vulkan version of that:

    #version 450
    struct Material {
Despite the name, GLSL is still used all over the place in Vulkan pipelines. The site teaches you the shader approach (rather than the fixed function pipeline of the 90s) which is what the "modern" Vulkan stack uses too.

That was the absolute minimal example of where "fundamentals" immediately devolve into a very specific code targeting a very specific API. See also sibling comment: https://news.ycombinator.com/item?id=49027094