I agree with you right up to how exactly does the M1 chip affect the final UX? A different keyboard, screen, touchpad, etc. all make a difference but why does the chip make a difference?
Everything runs faster, cooler, quieter and battery lasts longer. Is that not part of the product UX?
The Apple chips are made for running macOS/iOS. Seems there are some hardware instructions that are tailor made for increasing the performance of Apple software so they can make sure everything is working toward a common goal.
They are trying to compete, and have different levers to pull with varying success. When the performance per clock or per watt levers don't work well enough, then they increase the power, and the end result is heat and inefficiency.
On the flip side, integrated solutions add another lever... writing hardware that does exactly what your software needs to improve the user experience.
AMD, ARM, and even Intel have some cool, efficient solutions, but not across their whole portfolio of products, and not at the higher ends of performance. But they are always competing, incrementing and working to get closer to that ideal.
Apple was able to focus on their exact market segment and get there rapidly.
It allows apple to focus on what they want without being limited by and two their hardware provider’s strategy.