DC apt repos for Debian-13 pretty please?

@morgwai666 , thank you very much!

If others run into the same issue, my files look like this now:

/etc/modules-load.d/nvidia-drm.conf

nvidia-drm

/usr/lib/systemd/system/lightdm.service

[Unit]
Description=Light Display Manager
Documentation=man:lightdm(1)
After=systemd-user-sessions.service

# replaces plymouth-quit since lightdm quits plymouth on its own
Conflicts=plymouth-quit.service
After=plymouth-quit.service

# lightdm takes responsibility for stopping plymouth, so if it fails
# for any reason, make sure plymouth still stops
OnFailure=plymouth-quit.service

Requires=systemd-modules-load.service
After=systemd-modules-load.service

[Service]
#ExecStartPre=/usr/bin/sleep 3
ExecStart=/usr/sbin/lightdm
Restart=always
BusName=org.freedesktop.DisplayManager

[Install]
Alias=display-manager.service

dmesg

...
[    7.903125] [drm] Initialized nvidia-drm 0.0.0 for 0000:01:00.0 on minor 1
...

/var/log/Xorg.0.log

...
[     9.068] (II) Applying OutputClass "nvidia" to /dev/dri/card1
...

Everything works perfectly, no errors!

@morgwai666 , the changes in /usr/lib/systemd/system/lightdm.service are not required, as systemd-modules-load.service is an indirect dependency of lightdm.service already:

systemd-analyze critical-chain lightdm.service

lightdm.service +79ms
└─systemd-user-sessions.service @5.493s +42ms
  └─network.target @5.471s
    └─NetworkManager.service @5.114s +355ms
      └─dbus.service @5.046s +63ms
        └─basic.target @5.038s
          └─sockets.target @5.037s
            └─uuidd.socket @5.037s
              └─sysinit.target @5.032s
                └─systemd-sysctl.service @4.994s +37ms
                  └─systemd-modules-load.service @458ms +4.195s
                    └─systemd-journald.socket @435ms
                      └─-.mount @374ms
                        └─-.slice @374ms

To be safe, I reverted all my manual changes. => VT1 error
Then I only created /etc/modules-load.d/nvidia-drm.conf with

nvidia-drm

Everything works flawless!
So the one additional entry in /etc/modules-load.d/ is all it takes…
Again, thank you very much for the hint!!!

For anybody having the same issue:

sudo sh -c "echo 'nvidia-drm' >> /etc/modules-load.d/nvidia-drm.conf"

In case anyone missed it from the packaging thread, Debian-13 support is official now :)