Being able to spin up an entire network of qemu+kvm VMs easily to do proper integration testing of my system configs was a revelation.
I found that building my configuration on a virtual machine was the best way to go. This way I was not desperate to get things working and simply moved when I felt like all my essential programs were in place.
I tend to recommend people start in the shallow end, using Nix on a regular Linux distribution (or even macos) for a while. Use it to manage development environments and for ephemerally accessing tools as you need them.
For me, the place that NixOS itself really shines is on servers.