The unattended setup is a large improvement, which also begs the question: Mac OS doesn't have an unattended.xml alternative for its installer?
A closer comparison here is Lumier, which provides a "Docker-like" interface to spin up VMs with a noVNC server: https://cua.ai/docs/lume/guide/advanced/lumier/docker
The key difference: dockur/macos uses QEMU+KVM, which only works on Linux hosts. It can't run on macOS hardware since Apple doesn't expose KVM. See: https://github.com/dockur/macos/issues/256
I thought this was a silly way to do it too, but upon reflection I don’t know if you can zero touch setup a Mac without registering a device in DEP.
You're both right - Apple's official zero-touch setup requires MDM + DEP, which needs Apple Business Manager (and yes, a DUNS number).
But for VMs specifically, DEP doesn't work anyway - VMs don't have real serial numbers that can be enrolled in Device Enrollment Program.
VNC-based setup automation is the only practical option - it's what the ecosystem has converged on for macOS VMs. Lume connects to the VM's VNC server and programmatically tabs, clicks, types through Setup Assistant.