Don't understand all the, "it can't be an M2" comments. Why? Why wouldn't they have a higher Mx in the more powerful machines? Guess what, they could easily have come out with the M1 for their more entry level "base" machines, and then come out with an M2 that goes in the 16" MBP, a larger iMac, etc. They could even release an M3 (or figure out how to allow multiple CPUs) that goes in a Mac Pro, and have all three processors selling at the same time.
When it is time to upgrade the Air, Mini, base iMac, etc. they could role the M2 down to it, clock it down or turn off cores as needed, etc. and role the M3 into the upgraded higher end machines.
Their iDevices don't always get the newest processor and they sell three generations of processors at the same time in the iPhones. Want the fastest iPhone, get the 12 with an A14, OK with medium, 11 with an A13, don't need as much performance, XR with the A12. Same thing happens in the iPads, need speed, get the Pro with the M1, medium, Air with A14, just need a tablet, get the iPad with an A12.
Heck, you can buy an AppleTV with two different processors right now. 4K is now an A12, HD is A8.
There is NOTHING that says they have to have the same M version in all their computers. It doesn't have to be an M1 base machines, M1X more powerful computers and M1XXXXXX-Mostest Superest in the Mac Pro.