It seems you are confusing Lemmy (which is one of the federated software powering the fediverse) with the fediverse as a whole. There is a lot of other soft running, like mastodon for most well known or peertube, providing other services, with others UIs :)
do you think the fediverse could replace popular social media
At the moment the internet is flawed, do you think the fediverse is the solution?