Personally I think ditching the old real mode systems will be a big boon to hobbyists, not a hindrance (sorry mode 13h users)! Linux/x86 Boot Protocol docs tentatively support this assertion (https://www.kernel.org/doc/html/v6.9-rc1/arch/x86/boot.html). What is helpful is having ACPI and UEFI and other conventions/standards in place.

ARM does have Base Boot Requirements (https://arm-software.github.io/ebbr/), that builds to something vaguely x86 like, but wow there's so many systems that still use hardcoded device trees. I haven't spent that much time, but just a couple hours is all it takes to figure out that uncompressing your dtb, applying an overlay, and recompiling a new dtb is awful & terrible & no way to compute. ARM is used so heavily in consumer devices that it's hard to see what would compel the greater ecosystem to do the right thing, to reform. I also can go read a deck like https://uefi.org/sites/default/files/resources/UEFI%20and%20... (UEFI and ACPI in Arm System Architecture) and appreciate, yeah, well, trying to be compatible & a good citizen is hard; there's specifications on top of specifications on top of specifications (Wei lists 17) to make it happen. x86 has benefited form a history of everyone tending towards intercompatibility, but there's nothing else in computing that's ever had such a strong overriding cooperation motive before.