Some recent BIOSes (e.g. from Dell) have dropped Legacy Boot Mode, at least for SATA disks. That's annoying when one wants to boot an existing disk with no UEFI partition¹.
Is is conceivable to make a bootable UEFI USB drive which only function is to bring in whatever is needed to boot from the internal SATA (AHCI) disk in Legacy Boot Mode, ideally with whatever booloader there is on that disk?
¹ Just got hit by this on a PowerEdge T40. I wanted to temporarily boot a (Clonezilla copy of a) Windows 7 disk, using the PS/2 ports for mouse and keyboard. Did this on an other PC.