Linux Boot option disappears from my system boot manager

grub-install has this option:

–removable
the installation device is removable. This option is only available on EFI.

From: https://wiki.archlinux.org/title/GRUB

My :robot: friend says:

The --removable option in the grub-install command copies GRUB’s core.img (grubx64.efi) to the location used by live USB sticks and similar devices. It provides the additional capability of booting from the drive if EFI variables are reset or the drive is moved to another computer. This can be useful when dual-booting with Windows or installing GRUB on a Mac, as it serves as a potential fallback strategy if a UEFI update deletes the existing UEFI boot entries.

I don’t know if systemd-boot supports installing on external disks, if any similar option is available for it or even necessary and if anything I said has any bearing on the issue.