Depends on the system, but on my ThinkPad X220, 'efibootmgr' lists an option to go into the ROM Setup. You just tell it to set it as a "BootNext" choice, and on next boot it'll go straight into the ROM Setup tool. As long as that's the case (not all, but many, do), it's easy enough to do.
For example, with mine, running 'efibootmgr -n 0000' selects the ROM Setup to boot on next reboot (and boots it only once).
Re: Reboot to firmware menu
For example, with mine, running 'efibootmgr -n 0000' selects the ROM Setup to boot on next reboot (and boots it only once).