Manipulate the UEFI Boot Manager. More information: https://manned.org/efibootmgr.
efibootmgr -u|--unicode
sudo efibootmgr -c -d /dev/sda -p 1 -l "\path\to\shell.efi" -L "UEFI Shell"
sudo efibootmgr --create --disk /dev/sda --part 1 --loader "\vmlinuz" --unicode "kernel_cmdline" --label "Linux"
sudo efibootmgr -o|--bootorder 0002,0008,0001,0005
sudo efibootmgr -b|--bootnum 0008 -B|--delete-bootnum