For now, this is the best I’ve found. I think there’s work on implementing this in actual lemmy, but this python script is the best option I know of ^.^ - you basically put your user account name and password for each account in a config file and run the script - though I’d make sure to delete the config file after you’ve done it, preferrably with some kind of secure-delete tool like shred on linux.
However, we don’t know yet if lemmy.world will defederate from Meta/FB, until the admins make some kind of statement on it nya. So I wouldn’t leave yet. Though making an account on a smaller instance might be a good idea anyway for simple performance reasons :)