It feels like M1 was the revolution, subsequent ones evolution - smaller fabrication process for improved energy efficiency, more cores for more power, higher memory (storage?) bandwidth, more displays (that was a major and valid criticism for the M1 even though in practice >1 external screens is a relatively rare use case for <5% of users).

Actually wasn't M1 itself an evolution / upscale of their A series CPUS that by now they've been working on since... before 2010, the iPhone 4 was the first one with their own CPU, although the design was from Samsung + Intrinsity, it was only the A6 that they claimed was custom designed by Apple.