In README and on the man page, you mention

       On a normal computer, using nodm is a big security issue because it would give anyone access to the computer.

       However, there are cases where automatic login is needed: for example in an embedded  system  such  as  a  mobile
       phone,  or  in a kiosk setup, or in a control panel for industrial machinery.  For those cases, nodm is simple to
       setup, lightweight, and it should do exactly the right thing.

OK, we now know the keyboard is now open to all comers.
But you neglect to mention one bit about the network. E.g,. in man xdm,
we see

       allow-all-access
              Disables access control in the server. This can be used
              when the .Xauthority file cannot be created by xdm. Be
              very careful using this; it might be better to disconnect
              the machine from the network before doing this.

So please also mention on the nodm README and man page, if one needs to
take special steps after installing nodm to re-secure ones network, or
if in fact, it is just as safe to connect ones computer to the network
with nodm running as it was before. Thanks.

All I know is pstree -alA says
  |-nodm
  |   `-xinit /usr/sbin/nodm -- vt7 vt7 -nolisten tcp
  |       |-Xorg :0 vt7 vt7 -nolisten tcp
  |       `-nodm
  |           `-ck-launch-sessi /usr/bin/dbus-launch --exit-with-session sh /home/jidanni/.xsession

This means X is started with host-based auth enabled, but without
mit-magic-cookie auth enabled.

Any client from localhost will be able to connect.
No remote client will be able to connect unless explicitly allowed
with 'xhost +'

NVY> Any client from localhost will be able to connect.
NVY> No remote client will be able to connect unless explicitly allowed
NVY> with 'xhost +'

Well I hope this is all documented on the nodm man page etc., with the
conclusion that "nodm does not open a backdoor for attacks via the
network", I suppose.