Unfortunately, as far as old iPads are concerned, one of the major issues with old iPads is the old safari version. And so old web standards. I've this potentially nice projects to mirror screens from the web browser, but they won't run on old iPads for this reason. Shipping programs to the old iPad will suffer the same issues: only programs specifically written for these old Safari versions will work.

I suspect this will be an issue for most old devices. Especially old Apple devices (though there's hope for the newer ones now that the EU requires them to allow other browsers), but for all devices ultimately.