In a similar fashion, it would be great to find a way to migrate your post history, not just your followers, between one service and another. So far it’s possible to request a backup, but only a few services allow importing said backup, let alone import a backup from a different provider (so far only Firefish, Pixelfed and its derivatives allow for the latter).
Not sure whether this implementation will be lighter on resources than what Lemmy currently uses. Given the overhead of the JVM though, it’s unlikely it will be supported by, say, a single Raspberry Pi