I prefer to avoid sideloading modified versions of the official iOS apps. That feels unsafe to run untrusted code, and I personally don’t want to review the code myself or build from source if that’s even possible.
There is no need to fuss with all of that, when there are plenty of good options on the AppStore.
Yatte [1] is a third party client built from scratch in swift ui. It can connect either Piped or Invidous servers. It’s available on all Apple platforms included tvOS. It runs way better than the official YouTube app.
Safari Extensions - I prefer watching YouTube in the browser. These extensions are universal AppStore purchases and work just as well on mobile as they do on desktop Safari.
Vinegar [2] is a Safari extension that blocks YouTube ads and replaces the player with the default WebKit html player. It makes using YouTube in the browser so much more tolerable. It’s helpful to have when you want to watch videos in 4K - something most Invidious or Piped servers struggle with.
SponsorBlock [3] also has an official Safari extension available.
[1] https://apps.apple.com/us/app/yattee/id1595136629
[2] https://apps.apple.com/us/app/vinegar-tube-cleaner/id1591303...
[3] https://apps.apple.com/us/app/sponsorblock-for-youtube/id157...