Following communities from Mastodon works about as well as following Lemmy ones - this is something I'd like to improve, but it's only very recently that we got a community that wasn't a meta / testing one. Following users is less spammy, 'cos you'll get their posts, but not all their comments to other people's posts, so maybe you could try following someone like Rimu.
Either way, Mastodon doesn't process outboxes and backfill old stuff, so you'll have to wait for something new to be posted.