I went to see Alexis Ohanian talk back when reddit was still small. He said they were doing it for fun, and meant it to be a small fun website. If memory serves, he called it tacky. I didn't like reddit back then, but over the years a big chunk of answers that were supposed to be on stackoverflow would show up on reddit. Google on the other hand started messing with search results to serve more ads, so appending reddit at the end of a query helped in many cases.
Making a better aggregator / search engine for the fediverse would be interesting. But its utility for the current content of microblogging is negligible. I wouldn't mind cutting out mastodon to be honest. It's just a bunch [british word for cigarettes] and hentai watching nazis arguing about which group is more retarded. It's entertaining, but it gets boring pretty much. You're guaranteed to offend both of those sides, so it's better to avoid the whole microblogging sphere. I guess Poland is a magical place where far right politicians go to anime conventions and pose for pictures with femboy attendants.
LBRY is more of a protocol like ActivityPub, but it's also a cryptocurrency. You can click download and get the file (unlike YouTube). It can distribute content in a bittorrent fashion, and that's a lot more scalable in the context of the fediverse. You need to ensure that the project gets properly funded, or it's not gonna be used. I understand your caution about crypto, but that could be a viable source of funding for this. You can buy compute with crypto, so it should cover most of your expenses.
I'd recommend you working on it alone, on the core at least. You don't need help if you're good at using LLMs. They can write most of the code for you, and even tests. Software teams of humans are slow and fragile. Single dev projects are a lot faster. Obsession moves mountains :)
I don't care much about open internet. I think it's open enough already. And most people want moderation (censorship). There is too much stuff out there, and most people are offended by a big chunk of it. It seems like the same people who want moderation also don't want the fediverse to searchable. Is that right?