The use of legacy or uefi are changes that users have to manually
themselves in their bios from manufactures default settings. There is no
tool that can do that for them or migrate those settings however users
should be able to change this for hardware around 2010.
The Installer would have to try to detect and make a choise sd-boot ( If
settings equall UEFI ) or grub2 ( If setting not equals UEFI ) depending
on it's results.
grub2 supports UEFI, doesn't have to be sd-boot
As an example here's the BIOS/UEFI history for Apple hardware.
2012 and older models only support legacy BIOS Mode
2013-2014 models support both EFI and BIOS with the default setting
being set on BIOS
2015 and later models only support EFI
Different manufacturers have different timelines and different default
settings but I think it's safe to presume from this year onwards they
will all drop the legacy support and default to UEFI.
Microsoft has been actively moving requirements to UEFI for some time
to in both server and workstation side of things as well as other
security improvements like the requirements for TPM2