Unless you're willing to root your phone, or use a developer certificate to run an unofficial app, I don't think there's any chance of getting an 3rd party youtube client on iOS. They're breaking youtube's TOS which is why they have to be side loaded on android.
I am willing to use a developer certificate to run unofficial apps...if there is code available i'd be happy to compile and load it onto my phone. I don't think there is though.
I just cannot go back to Android after years of dealing with garbage(I owned all the Nexus phones and gave up after Nexus 5) so my options have been to limit phone usage in favor of Desktop + start working on as many homemade/ open source versions of iPhone apps that I use as possible. Luckily most apps i'd be likely to have installed are just some downloaded data(text, audio, video) and some buttons. How hard can it be to scrape and rip the content and make my own container to serve that data?
For other apps like Youtube alternatives I am in search of an app.
Invidious and Piped should actually work quite well. Not apps, but work fine in a browser. That's what I'm using on the PinePhone and on regular computers. Though I don't know if Safari still has limitations that make it a pain to use. Invidious is a pain on the iPad 2 because of some dumb design decisions in Safari but I expect it to have improved since then. And maybe third party browsers will at last be allowed on iOS through third party stores, maybe also allowing SponsorBlock to be used on this platform.
I'm missing some features like being able to select a play next video easily, so I may look into writing an Invidious-based client of some sort for this, but they are so many things to do for a strongly limited time.
Maybe Piped has the features I'd like to have, I should check it out.
You can use an app currently in the App Store called "yattee" -- you can add an Invidious source in the settings, and viola you're good to go. I self-host mine, but you can totally point it at a community hosted one.
