One suggestion I saw a while ago was to use more general communities for things you're interested in and as it grows then the more niche communities can be made. Ex: post about a specific game you like in gaming up until enough people like it to make a sub for that game. Or post about a song you don't know in asklemmy until enough people do that to make whatsthissong
I totally get wanting the niche communities and, personally, I just lurk reddit completely not voting, posting, or commenting unless as a last resort if I really need to find info that Lemmy isn't able to provide.
It's a slow process and I don't think there'll be another boost of users in Lemmy until reddit does another thing that enshittifies it to annoy people to leave.
Yeah there are times where I'd want to make a community but the necessity of moderation makes it a big hurdle to even want to begin that process.