Ask HN: How hard is it to build a platform like Netlify?

I'm fascinated by Netlify, by its speed and neat developer experience. I want to learn more about the inner workings of such platforms and thought that the best way to do it is to build something like Netlify myself. Nothing stellar, just a simple proof of concept clone. Any suggestions on where to start and where to learn about the architecture of platforms like Netlify? I'm a moderately experienced frontend developer, I have some backend and DevOps skills, but it's mostly "street knowledge," and I don't have a CS degree.