Apple unified memory shares all over CPU, GPU and NPU, you can assign a lot of memory to run local models and there bandwidth is good, depending on the model.

AMD has something similar with their something something AI CPUs and they go up to 128GB at the moment. Apple can be way faster though. And you were able to buy a Mac Studio with 512GB back when RAM wasn't worth more than unicorn pee. For... I guess 10k though.