It's Fediverser. Yes, it is on github. Yes, I've posted about it, quite a bit.
I asked prolific users to join, I offered help to admins to set it up. I even offered the topic-specific instances to the wider community. None of these efforts were well received.
I feel like we are talking about different things. You seem to be more focused on Reddit vs Lemmy, and I am talking about the "Closed" social networks vs the wider Fediverse.
The comparison is not to Reddit. It's Instagram/TikTok/YouTube. Maybe you heard of those: it's a place where WNBA players making $100k/year by playing can make $20k per Instagram sponsored post.
First, lumping together all these three ideologies as one single block is a bit handwavy. Second, I am not talking about "anti-corporate". I'm talking about anti-business. If you think that the majority of people are that extreme in their political positions, I'd guess your worldview is quite skewed.
This is a strawman: I'm saying "We should not have to rely on open registration instances and hope that the admins get enough funds to keep going", which is not the same as "all instances should be paywalled".
I think if we didn't have as many open instances, we'd end up with more people self-hosting and running a server for their own friends, or we would start hearing from students asking their universities to run a server for them, or we would get hyper-localized instances where some group would pool resources to run a service for themselves, etc.
Again, it's not just about reddit. Also, it's about having places where politics are not such a proeminent part of the discussion. E.g, Threads got a lot of their initial momentum by avoiding politics and getting sports journalists to post about NBA and football.