Friendica does this already! This is how I see your comment:

@Bebo
You can always migrate, but sadly there is no way to import your profile directly from Mastodon. The two best apps, Fedilab and Relatica, are fine but rather limited in functionality, so I often end up using the web version.

I love both Mastodon and Lemmy, but they usually don’t federate very well with each other, so one cannot replace the other: Lemmy users cannot see microblog posts which aren’t connected to any community and Mastodon doesn’t show the body of Lemmy posts. Currently trying out Friendica, which manages all parts of the Fediverse reasonably well.