this will work on BIOs systems and possibly systems with CSM mode which emulate legacy BIOS in efi.

UEFi has a different interface, not IVT to make BIOS calls and no code to catch them. you would use raw disk access protocols its really easy maybe even easier once u know how to use handles and protocols in uefi to implement this for uefi.

the problem then becomes secureboot, which if enabled will be bypassable only via misconfigurations or exploits. it would refuse to from the usb or an alternate disk image when set up correctly and no exploits are known by the dumper.

for that reason there's i think attacks that can be done by removing the ram sticks and sticking them into specialized device to dump it.

theres some tutorials on how to connect ram sticks to breadboards etc. , but idk if theres other details besides raw talking to the ram and dumping it that would make it less reliable. (not sure how long bits are retained, usually ud wanna reboot and instant dump afaik if its totally off for a while its unrecoverable but i am not really sure on that last part. (so removing it to seat them in another device might make bits decay and data less reliable?)