Such mechanism already exists. Look for the comment by @nightpool
It works best between Mastodon instances, but between different apps the migrations are often also supported. New apps like GoToSocial have the migration still as open issue sitting in their tracker, but will support as well.
It works best between Mastodon instances, but between different apps the migrations are often also supported. New apps like GoToSocial have the migration still as open issue sitting in their tracker, but will support as well.