Hi all,
I installed openbox. It works. Systemd starts openbox via this command.
systemctl enable xdm.service
After system booting, XDM login screen says welcome 
I think XDM cannot autologin. If true, how to autologin to openbox?
Or, alternative way to start openbox directly without login window?
Thanks.
xdm is probably the display manager I have used less - so I have no idea on how to do that.
But you can autologin using most displaymanagers lxdm, lightdm, sddm.
No matter how you flip the coin the system will need a username.
If you do console you will have to provide username and password - then run startx.
If you do display manager you can preload the config with a username which then will be used to start the graphical system.
The backdraw to doing that is that no keyrings are unlocked because that is impossible without password so - at some point - you will be asked for authentication.
Executing any task as superuser - will still require authentication - there is no way of turning Linux into Windows XP.
On Arch wiki read XDM - ArchWiki
Passwordless login
In order to enable passwordless login for XDM, add the line below to
/etc/X11/xdm/Xresources:xlogin*allowNullPasswd: true
I know all systems require user and password.
On Ubuntu or Raspbian mini image distro, When I installed openbox, autologin is possible. After edit getty@tty1.service for autologin user, openbox starts via startx command in .profile file directly.
It does not work for passwordless login.
I installed xdm-archlinux package. After disable xdm service, enable xdm-archlinux service but same result occurs.
I’ll try lxdm, lightdm or sddm.
I prefered & installed slim ( Simple Login Manager). No problem.
remove display manager
yay -S xlogin-git
To enable automatic login at boot, execute:
systemctl enable xlogin@<username>
it is a good idea to put in .bash_profile a control on console number:
[[ -z $DISPLAY && $XDG_VTNR -eq 1 ]] && exec openbox
or whatever,so if doenst work, Ctrl-Alt-F2 to start a non graphic session
If you wanna autologin as root (or others) directly without login window, it may use nodm.
https://wiki.archlinux.org/title/Nodm
On a normal computer, using nodm is a big security issue because it would give anyone access to the computer. I am using it on raspberry Pi without network.