[jraph]

Sure, that belongs to the very few valid use cases.

I got an iPad 2 from a relative, I do detect its user agent on my private Invidious instance to send it transpiled/polyfilled JS instead of the original one.

Of course it would not be the correct solution if Apple did not forbid other browsers on its hardware, the correct solution would then be to install a recent Firefox version on it. It would also allow a shitload of other stuff to work, like subtitles on fullscreen videos and autoplay on the next video, playback of videos protected by HTTP basic auth, as well as Let's Encrypt SSL certificates.

The device's browser should send a "X-I-m-dumb-and-my-manufacturer-likes-to-piss-everybody-off: true" HTTP header to avoid relying on its user-agent though.

[jeroenhd]

FWIW you can get Let's Encrypt working on outdated Apple hardware by manually loading the CA certificate.

[jraph]

I could import the root certificate but instructions for activating it didn't work, they seem to apply on more recent versions of iOS.

[jeroenhd]

I've done it on iOS 9.3.5 and it worked in Safari at the very least. You need to import it first and then activate it from the settings afterwards, I believe.

iOS changed the exact procedure a few times so you may need to Google around for the exact steps you need to follow.