That's pretty simple (lets think you use /dev/sda1 for /boot/efi - basically i would not even need -d/p in that case and /dev/sda2 for /), try this
instead of root=/dev/sda2 you could use in the case you have got gpt this:
Thats usually not needed for only 1 internal hd, but would not hurt of course. A partuuid is the id of the partition and NOT the id of the filesystem, this is not supported without initrd. It is possible to boot with initrd as well, but i think you wanted to boot with max speed.
sudo cp /boot/vmlinuz-$(uname -r) /boot/efi/EFI/ubuntu/linux.efi sudo efibootmgr -c -d /dev/sda -p 1 -l '\EFI\ubuntu\linux.efi' -L 'Ubuntu direct' -u 'quiet root=/dev/sda2'
echo root=PARTUUID=$(blkid -p -s PART_ENTRY_UUID -o value /dev/root)