If you could build an OS for software dev, what would it look like?

We already have that is called Pharo or Glamorous toolkit. I guess a way to describe it is imagine a virtual machine, like vagrant... that comes preloaded, with your editor, your database and every app you coul imagine. Then each app is an object that is callable from your peogram.. is like if you were developing an app and could import an excel function in your own code... even better script excel from your own code.

Thenwhen your app is ready, just deploy your machine.

Smalltalk is an elegant weapon of a more civilized time.

An environment for software development is much more than an OS. There are tools and systems that are installed onto it. People also have preferences, so there really isn't a one size fits all.

A better question may be "How do you maintain parity for your developer systems?"

This is more complex than using something like Packer or Ansible to create a consistent VM. How do you know if the developer changed something manually?

Just like the target production OS. A whole raft of deployment problems goes away. You teach people how to swim in a pool, not in a shower.

Unix/Linux has the tools I need for development.