Meh, discoverability isn’t really as much of a problem as people think it is. Add videos to your Watch Later from your Subscriptions tab, and as YouTubers you like do collaborations or recommendations, you’ll discover similar channels. Sometimes you’ll find a channel from a creator’s website or from a podcast, or from a social media feed you follow. It’s a world-wide web, and as much as companies try to sell you the myth of discoverability-as-a-service, that’s just a marketing tool. They need it to push ads and drive retention. You don’t need it at all, because the web already does that.
I’m almost entirely off of black-box recommendation algorithms, and I still find new things I like. In fact, my to-watch, to-read, and to-listen queues are too big to handle in a reasonable amount of time. I regularly have to unsubscribe from things I don’t like as much anymore or risk getting deluged with too many things I want to see. But the bonus is, I don’t get anything I don’t want to see.
Write your own algorithm. It’s a better life, and it barely takes any more time or effort. Just change your bookmarks and be willing to put in an extra click or two when you want to consume something.