Except for Safari, which is tied to OS updates. And of course Apple don't allow other browsers on the store so now you're stuck on the outdated browser.
I know my old iPad has issues with Home Assistant's web interface for example.
Yeah safari barely works on it, which is maybe half because its outdated and half because websites have gotten a lot heavier since then. The iPad had a tiny amount of RAM by today‘s standards. Something like 512 MB, or even 255? iOS was aggressive about killing apps (esp safari) when RAM runs out. Not sure if it can even swap, or could back then?
I know my old iPad has issues with Home Assistant's web interface for example.