For YouTube frontends: On the Linux desktop, there is FreeTube, on IOS there is yattee (IIRC), then there are web based front ends from invideous.

Louis Rossman mentioned the other day that they are in the process of creating an app that will allow you to follow your chosen creators across multiple services, so that you can continue even if their primary platform removes them.

If you’re looking for YouTube alternatives, check out Peertube, Odyssey, and Nebula (I haven’t looked at Peertube or Odyssey in a while, so I can’t comment on how they are doing).