Looking at the LemmyHttp docs, mentioned above, it looks like you probably want to use the ListCommunities resource with the type_ ListingType of "Subscribed".

To do that with Plemmy, it looks like you want to use LemmyHttp(...).list_communities(type_='Subscribed').

Fair warning, I’m making this comment just from reading docs and source code, I haven’t had a chance to try this yet.