Jobs set the groundwork, but their silicon didn’t hit the ground until 2013 with the a7
That was my first thought. Is the M1 the result of true innovation or simply vertical integration?
Yes
What's your definition of "true innovation"? No, Apple did not invent an ARM ISA CPU, but the they also pushed the hell out of all available technology in their design and implementation. The amount of innovation in that far surpasses pretty much anyone else in the mobile space. You should really read into what they've been doing with their in-house SoC team since the A7.
Ryzen 4000 is competitive at 7nm, given how huge the R&D budget was and how long the development time was, if the M1 wasn't as good as it was it would have been a let down
Apple was definitely one of the earlier backers of ARM through Acorn back in the 80s.