You usually use Vagrant to provision a machine with a suitable image and then use some other tech to setup your environment on that image. Common choices are Chef, Puppet or Salt, last time I checked.

You can use NixOS to replace both the OS image and the configuration tech.

Watch https://youtu.be/tl9I-R83lKo for a quick overview. It me in the video btw.

Great run-through, thank you!

You don't use Vagrant for your desktop, do you?

No no no. Vagrant is for spinning up dev environment VMs with a virtualization tool like VirtualBox.