I was inspired by https://bossportsnation.com/2024/02/07/where-are-mls-fans-gathering-online/ so I did some analysis of where MLS fans are hanging out in the fediverse. You can find the data here: https://docs.google.com/spreadsheets/d/1bh70eldw1Xf04sUjVFx0KIhWy97UF_HZTYwSSspEwD0/
I also don’t think Lemmy has that feature, though many clients make it easy to manage multiple accounts, which you could use to approximate that behavior. Mastodon has lists, though, which totally do that, just in case you’re into that format as well. I definitely agree that I want “multi-communities” — I’ll see if I can scare up a GitHub issue to comment on with our use case to see if that encourages the dev team to pick up the feature.