PCs have a BIOS/UEFI that provides hardware discovery and abstraction to the OS, while phones lack that and need the OS to know what hardware to expect.
20 years ago when the predecessors to modern smartphone hardware were being designed, there probably would have been meaningful costs to adding that kind of flexibility. There probably wouldn’t today, but there’s also no motivation for phone makers to do it.
PCs have a BIOS/UEFI that provides hardware discovery and abstraction to the OS, while phones lack that and need the OS to know what hardware to expect.
20 years ago when the predecessors to modern smartphone hardware were being designed, there probably would have been meaningful costs to adding that kind of flexibility. There probably wouldn’t today, but there’s also no motivation for phone makers to do it.