In essence, Apple's first try at designing its own processors has resulted in cores that are superior even to AMD's Zen 3 when you compare the chips on a clock-for-clock basis. So how did Apple achieve this feat? Developer Erik Engheim delves into the details over here. He also explains that it will be hard for AMD and Intel to copy the tricks Apple performed because they're limited by x86 and because what Apple is doing right now is a very different business model.
Apple basically controls the entire Mac computer as well as the software that comes with it, which provides an unprecedented level of freedom. AMD and Intel on the other hand sell processors that can be mixed and matched with various chipsets, motherboards, RAM, GPUs, etc. These are then usually paired with an operating system designed by yet another company (aka Microsoft). That results in certain limitations that Apple doesn't have.
Sure Intel and AMD may simply begin to sell whole finished SoCs. But what are these to contain? PC makers may have different ideas of what they should contain. You potentially get a conflict between Intel, AMD, Microsoft and PC makers about what sort of specialized chips should be included because these will need software support.
For Apple this is simple. They control the whole widget. They give you e.g. the Core ML library for developers to write machine learning stuff. Whether Core ML runs on Apple’s CPU or the Neural Engine is an implementation detail developers don’t have to care about.