Keep in mind by in large subreddits did not migrate. There may be equivalent communities but not migration of subreddits. The big issue that Reddit has is that you do not need to migrate a community. You just need to find a similar one. Just go and use the search engine. Either the threadiverse wide one: https://browse.feddit.de/, or the one on your instance. The instance one is generally limited to communities someone on the instances has subscribed to already, but on larger instances it is pretty complete.
Keep in mind by in large subreddits did not migrate. There may be equivalent communities but not migration of subreddits. The big issue that Reddit has is that you do not need to migrate a community. You just need to find a similar one. Just go and use the search engine. Either the threadiverse wide one: https://browse.feddit.de/, or the one on your instance. The instance one is generally limited to communities someone on the instances has subscribed to already, but on larger instances it is pretty complete.