Every android I had died/missed updates less than 2 years after I bought it, exception to the original moto x that was the pinnacle of android for me
The iPhone 6 lost support in 2020 or 2021.
The original iPhone SE (the little one from 2016) is equivalent to a 6s (both use A9) and it’s widely expected that Apple will drop support this year.
However the newer/bigger iPhone SE that was released in 2020 has the same chip as the iPhone 11, the A13. It should still be good for many years.
You likely are using a version of the App Store which doesn't support pinning older OS releases on older app releases either -as soon as they released a build for iOS 7, the iOS 6 version would no longer be accessible.
You are also missing about seven years of security updates, including several browser-accessible remote exploits. Not using Safari would be a good idea.