You can have as many forks as you want, but that's a software engineer's solution to a social problem. Lemmy is the "name brand" now for ActivityPub based federated content aggregation, and it will be orders of magnitudes more difficult to get support for forks, both from a contributor and from a user perspective.
Just look at last year's Twitter migration, and the sea of people complaining about Mastodon not having features they felt were a requirement for adoption, while also ignoring every other Mastodon alternative on the Fediverse that had everything they were looking for.