Just some modifications to Debian Unstable system to make it boot ASAP. It works with UEFI systems.
Results on almost clean Debian install with gdm3:
Startup finished in 3.285s (firmware) + 69ms (loader) + 1.171s (kernel) + 1.032s (userspace) = 5.558s
graphical.target reached after 1.020s in userspace
Installation:
# TODO: install files in repo
# install systemd-boot (zero delay), but keep grub as different UEFI entry
bootctl --path=/boot/efi install
# regenerate initramfs
update-initramfs -u -k all
# disable this horrible service !!!
systemctl disable NetworkManager-wait-online.service
# check boot entries
bootctl --path=/boot/efi install