With an iPhone 8, I know I'm the one "at fault" at this point for sticking with this device, stuck on the wrong side of an inflection point in screen size/resolution from the introduction of "edge" displays all across the ecosystem. I might expect Apple themselves to tune their first-party apps for my device for as long as they claim to support it; but I don’t expect App Store devs to do so. They’re shipping cross-platform designs on a tight schedule, for screens that are almost-exclusively twice as large and high-resolution as mine.

The iPhone SE case is more concerning, because it's still for sale at the Apple Store. This means Apple is claiming it's fit-for-purpose for at least some use-cases. (Maybe that claim doesn't extend to "running apps from the App Store", though.)

I feel like, at this point, the SE is almost the same as the iPod Touch—it's not a thing you get to take advantage of the Apple app ecosystem; it's more a thing you get to either use Apple's first-party apps for basic use-cases, or because it's a very cheap automated development smoke-test deploy target (roughly the iOS equivalent of a Mac Mini.)