> Compiling shaders directly from a high level representation to the GPU ISA only really happens on consoles.

No, that's not correct. In fact, it's mostly the other way around. Consoles have known hardware and thus games can ship with precompiled shaders. I know this has been done since at least PS2 era since I enjoy taking apart game assets.

While on PC, you can't know what GPU is in the consumer device.

For example, Steam has this whole concept of precompiled shader downloads in order to mitigate the effect for the end user.