If you’re going to go into that much detail, you’d also have to consider when the device was bought and when the new OS came out. But honestly, I don’t have the drive or see a point. I’ll still prefer a 1, 2, or 3-year-old m series iPad Pro over the latest Air, when similar price range or cheaper. That’s mainly because of the display, then the aesthetics, and then features/performance in some generations. And even if the new OS has extra support for ‘x’ months on latest Air, I don’t keep iPads, computers, or phones for 6 + years when that support becomes somewhat relevant. But I guess if you are one that likes to keep devices that long, your point might be relevant. Let’s remember, these devices will still continue to work fine for many years without the latest OS support.