Ask HN: How does one create a service like Vercel or Heroku?

As the title says, could someone lay out what would it look infrastructure/architecture wise to create one of those services?

I spend most of my time creating CRUD apps but I'm finding out I want to learn more of how the web really works.

For example, I know that for Heroku there are Open Source projects like CapRover [1] that fulfill similar needs. Would it be good to study the code of that project to understand how it works?

What technologies should I study? I'm thinking I should learn: * Docker * Nginx * AWS (S3, EC2, API Gateway, ...any other?)

Thanks in advance!! [1]: https://github.com/caprover/caprover