I can't speak for these specific laptops, but unlike x86, ARM generally doesn't have a way for an OS to discover the available hardware, and most ARM platforms historically didn't do anything to help. There is a standard for UEFI on ARM where the UEFI is supposed to tell the OS about the hardware, but as far as I know this is only a thing on ARM servers and these laptops might not support it.

Without any way of probing for hardware or getting the information from UEFI, Linux has to somehow be compiled with all the info about the hardware built-in. And the build will be model-specific (there's a way to pass a file describing the hardware to Linux from the bootloader which enables a single kernel to be used on multiple models and have just a small part of the bootloader be model-specific, but somebody still needs to make that file and the manufacturers clearly don't intend to do that).