But doesn't the Apple M series NPU support FP8, and as it's a monolithic die (except for the GPU in the M5 Pro and Max) it could be argued it has hardware FP8 support, no?

By that logic, on the M4 (which still has the GPU on the same die as the CPU), CPU cores have hardware accelerated raytracing, which is obviously nonsense.

I thought the M5 had FP16 support, and not FP8.