When the API changes came in on Reddit it appeared to cause quite a few people to shift to Lemmy, but not that many. I've said this before in other posts but the onboarding experience for Lemmy is awful for your average joe. From what I've read it was the same situation for Mastodon and that is why Bluesky took off instead.
There needs to be a clear concise point of entry for new users to the Fediverse that empowers users to quickly customise what they want to see. Most people don't care about how the Fediverse works and its benefits, they just want to consume content.
If I were technically capable and had the drive to do so I'd create a single onboarding site that would ask the user a few preference defining questions, chuck them on an instance that is relevant and apply some filters so they don't get spammed with anime posts if that isn't their thing. Oh and maybe show a couple of mobile apps.