Honestly, for me the only advantage of moving from A12X to M1 is RAM, the speed increase is barely used by iPad, and while I am sure some people will argue that for the M1 changes everything for them, I am also certain that most people would be fine with a an iPad pro that has A12X/Z 8GB RAM for a couple hundreds dollar cheaper than M1. Many actually buy refurbished for this very reason, despite the lower RAM. And the SSD speed difference is also pretty much irrelevant on these devices, they are both basically instant. And the Samsung is a sort of A12X with more RAM. Fast enough that it does not matter.
As I have said, it's like PPI, once you get to Retina on a laptop, going up to 4k has diminishing returns.
These CPU and SSD speed comparison sound like transposing desktop comparisons (where they matter more) to much more limited systems (and in terms of being limited iPadOS is number 1, especially with multitasking).
Concerning support, I don't think you can compare iPadOS to Android.
1. What are you looking for in an update? Security? Well that's 5 years, not 4. And honestly, security on tablets cannot be compared to security on desktop OS. Millions of people use unsupported tablets safely every day to watch videos, read books and even browse the internet. Most malware targets desktop systems and Windows in particular and if you don't install strange apps or better yet do not install any new app on an unsupported tablet it can be used for many years after end of updates.
2. Updates on iPadOS are not guaranteed, sure the air 2 got a lot, but what if Apple this year decides to cut the 1st gen pro (2015 and 2016) and even the 2017 iPad 5 together with the air 2?
3. App compatibility on Android is quite a bit longer than on IOS. IOS 9 is basically unusable at this time to run anything. The older Android 5 still runs a ton more apps and my old lenovo tablet on Android 5 is still compatible with most apps, contrary to my iPad 2.