My basic Debian 13 preseed configuration (version 1) for Proxmox
d-i debian-installer/locale string en_US.UTF-8
d-i keyboard-configuration/xkb-keymap select us
d-i netcfg/choose_interface select auto
d-i netcfg/get_hostname string debian-template
d-i netcfg/get_domain string debian-domain
d-i netcfg/disable_autoconfig boolean true
d-i netcfg/dhcp_failed note
d-i netcfg/dhcp_options select Configure network manually
d-i netcfg/get_ipaddress string 192.168.178.30
d-i netcfg/get_netmask string 255.255.255.0
d-i netcfg/get_gateway string 192.168.178.1
d-i netcfg/get_nameservers string 192.168.178.1
d-i netcfg/confirm_static boolean true
d-i netcfg/wireless_wep string
d-i mirror/country string manual
d-i mirror/http/hostname string deb.debian.org
d-i mirror/http/directory string /debian
d-i mirror/http/proxy string
d-i clock-setup/utc boolean true
d-i passwd/root-password password omega
d-i passwd/root-password-again password omega
d-i passwd/make-user boolean false
d-i partman-auto/method string regular
d-i partman-auto/disk string /dev/sda
d-i partman-auto/choose_recipe select atomic
d-i partman-partitioning/confirm_write_new_label boolean true
d-i partman/choose_partition select finish
d-i partman/confirm boolean true
d-i partman/confirm_nooverwrite boolean true
d-i base-installer/install-recommends boolean false
d-i base-installer/kernel/image string linux-generic
tasksel tasksel/first multiselect standard
d-i pkgsel/include string qemu-guest-agent build-essential openssh-server sudo
d-i pkgsel/upgrade select none
d-i pkgsel/update-policy select unattended-upgrades
d-i grub-installer/only_debian boolean true
d-i grub-installer/bootdev string /dev/sda
d-i preseed/late_command string \
in-target systemctl enable ssh; \
in-target systemctl enable qemu-guest-agent; \
in-target systemctl start qemu-guest-agent; \
echo 'PermitRootLogin yes' > /target/etc/ssh/sshd_config.d/99-packer.conf; \
echo 'PasswordAuthentication yes' >> /target/etc/ssh/sshd_config.d/99-packer.conf; \
echo 'PubkeyAuthentication yes' >> /target/etc/ssh/sshd_config.d/99-packer.conf; \
in-target chmod 644 /etc/ssh/sshd_config.d/99-packer.conf
d-i finish-install/reboot_in_progress note