I've been using a youtube frontend called pockettube, where I could make lists(channels) for content I like, without youtube forcing me what to watch.
Example. I have an Art and Food channels with my favorite content creators, I get to see the list in order of newest videos first, totally bypassing youtubes forced interface.
In fact, if people started creating front ends to youtube with real search/suggestion engines, you could find new content and help the less viewed but good content that gets bypassed.
Grayjay is great, since it uses multiple video providers, but you still have to "Know" who to follow. The search "Knowing" part is still word of mouth, random change of seeing a creators video, or the platforms showing it to you. Combine the 2, and it would be unstoppable.
I think if someone came up with a external database of content providers on multiple platforms that allows apps like grayjay/pockettube/etc to find new content, that is the missing piece.