I signed up for Nebula and I barely use it. It's poorly curated, there's seemingly no recommendations so I'm just in a wash of content with no direction.
I think that it's probably worse the more you use it. The more I subscribe the more garbage I get recommended I think. I watched the raw footage of some of the Heard v Depp trial (as in - uncut, direct footage) and I don't know if my algorithmic output will ever recover - the shit I get recommended now is of zero interest to me. Similarly, I looked up a few 'how tos' for some games, and now I get tons of 'gamer' content. The other day Youtube recommended Ben Shapiro to me lol
But that's just the main page. If I'm already on a good video the sidebar recommendations are decent.
If there's something better please let me know, I hate Youtube as a construct and I think that the monetization of horribly low content is damaging in ways I can't even predict, but also I gotsta have my "expert on topic talks to me about interesting thing" content.