Couldn’t a client app manipulate the URL from the fetched post content before displaying, even on iOS?
On Android you can assign alternative apps as a standard app for specific URLs. This works just fine without root etc. via the regular app settings. E.g. in my case YouTube links from everywhere (mail program, browser, lemmy, …) open automatically in the privacy-friendly NewPipe app from F-Droid.
Where have u set this option I can’t find it in settings some time ago I have probably set YouTube as default since I can’t chose a different app …
In Android 14: Settings / App Settings / / Default opening (Terms might be slightly different. As my Android isn’t in English, I had to translate it.)
First go to the official YouTube app (if installed) and remove the binding. Then, go to NewPipe (or your preferred client) and set the binding there.
