All Apple devices have a NPU which is potentially able to save power for compute bound operations like prefill (at least if you're ok with FP16 FMA/INT8 MADD arithmetic). It's just a matter of hooking up support to the main local AI frameworks. This is not a speedup per se but gives you more headroom wrt. power and thermals for everything else, so should yield higher performance overall.

AFAIK, only CoreML can use Apple's NPU (ANE). Pytorch, MLX and the other kids on the block use MPS (the GPU). I think the limitations you mentioned relate to that (but I might be missing something)