_systemd-networkd_ includes a `.network` configuration file for WiFi
devices in station mode, but it is disabled by default. Adding this
symlink will enable it, allowing WiFi devices to come up automatically
on boot.
Until I implement some kind of self-provisioning process for these
machines (supposing I ever do), I need a way to log in and
configure/troubleshoot. I don't think there's any particular security
concern by having an auto-logged-in root shell on the UART console, as
accessing it needs physical access to the machine.
