>Take one look at what is going on in the risc-v world with nearly every soc having its own fork of the linux kernel
There aren't that many RISC-V Linux-capable SoCs out there, and the ones I know all can boot a generic Linux (relying on SBI for e.g. timers or console i/o), and have ongoing efforts for upstreaming drivers.
It's a much more serious problem on ARM, which does not have anywhere as much platform nor boot standarization.