Lemmy is just a UI frontend for the Activity Pub protocol. It’s tuned for Reddit-like link aggregation, sure, but anything on the Fediverse can be accessed by Lemmy, in one way or another.
Case in point - you can actually follow Mastodon profiles on Lemmy. The profile itself gets displayed as a community, and each publication becomes a post. The limitation is that comments and upvotes you make into the posts don’t propagate back to Mastodon, they live as ghost metrics that only Lemmy users using your instance can see. Regardless, you can most definitely follow BBC on Lemmy.