The iPad 2 is blocked on Safari 9, which was released in 2015, only 4 years later.
The Samsung Galaxy S II was released in 2011 too [0]. It was running Android 2.3.3, but could be upgraded to Android 4.1.2. The latest Firefox version to support this version of Android, Firefox 68.11.0, was released July 27, 2020, 9 years later. The web is way more usable today on a 2020 browser than on a 2015 browser. And in 2020, the browser was current on this device!
But the story does not end there. Today, you can install Lineage 18.1 / Android 11 on this device [1]. To be fair, many things don't work on this port, but there's an official Lineage 14.1 / Android 7 Lineage ROM [2] for this device, last built on 2018, 7 years later, on which current versions of Firefox mobile work, because Firefox supports Android 5 and later [3]. And since it is an official Lineage release, you'd expect the device to work correctly on it.
You can have a current browser on this 12 years old device. This is possible because most Android devices are not completely locked out from custom OS development.
> Probably apart from desktop
But that's my point actually. To be fair, the Galaxy sII is an incredibly lucky device compared to most Android devices (however, iPhones and iPads are also usually compared to the Samsung Galaxy ones). And don't be mistaken, I also strongly dislike Android. A computer bought from 2012 can be upgraded to an up-to-date Linux distribution without any issue. There's nothing fundamental to mobile devices that should prevent this.
[0] https://fr.wikipedia.org/wiki/Samsung_Galaxy_S_II
[1] https://www.xda-developers.com/samsung-galaxy-s-ii-unofficia...
[2] https://lineageosroms.com/i9100/
[3] https://en.wikipedia.org/wiki/Firefox_for_Android#Platforms