I used to see reports that you could "carry over" your account from one instance to another. Do you have any details on this, or whether this also works between different services (e.g. KBin and Lemmy)?
This works on Mastodon, but not on Lemmy/Kbin (yet). Migration between Lemmy and Kbin in general could be tough since they're completely different softwares and Lemmy lacks support for several Kbin functions (such as Boosts and Microblogging).
Account migration between Lemmy instances has been requested on GitHub but I don't know much beyond that. If you just want a profile redirect it might not be too complicated, but migrating full post and comment history is a different story.
Scripts have been created to transfer settings and subscriptions from one Lemmy account to another, however:
Being able to link/synchronize accounts a cross instances would be huge for continuing to use lemmy when your main instance is having trouble or goes down.
And I think if accounts were globally federated so that you could just log into any instance, it would take away the main complaint many people have when they claim lemmy is confusing.