In Mastodon, I believe you can -- but it's more of a Twitter-dump than something as well-separated as subreddits. Each time a user follows someone from a new server, that server's "federated feed" is added to the homeserver of that user. It's not perfect, but it does mean that federated feeds do spread organically (and it does result in single-user instances spam-following everyone so that you can get a more cohesive feed).
The "federated timeline" tab should be what I'm describing -- though to be honest the last time I talked to any of the mastodon folks about this was more than a year ago (the semantics might have changed).
