This *works*, and it's possible to edit files in one virtual machine
while having those files instantly be updated in all other virtual
machines. Note that the host will also have access to the files, which
ultimately means that directory sharing is quite useful (and convenient).
This is a working example of using the modules in our existing
configuration to start a network of virtual machines with
nixos-build-vms. Note that VMs take longer to start up in this case than
nixos-rebuild build-vm, and that said VMs may lack certain functionality
(such as dynamic resolution in GNOME) that would otherwise be present
with build-vm.
Although networks are certainly cute (and I'm glad that I feel familiar
with them thanks to my better understanding of Nix), they do seem less
convenient than nixos-rebuild build-vm and don't appear to support Nix
flakes. Networks therefore seem more useful for running multiple one-off
services that couldn't otherwise be ran in a container.
