Lemmy

Some Lemmy compatible platforms allow you to see both Lemmy style content and Microblog style content in the same platform. Some also let you follow individual users. Something like that could work, as long as it's an additional option and not a change to how communities currently work.

Mixing hashtags with communities sounds like a bad idea because of how much content would come in at once. For example, there are a few RSS feed communities and already those ones are overwhelming to keep up with. Most posts sit with no comments and 1 vote, which doesn't work for the vote & comment based way we organize content here.

We can improve how we federate these platforms together, but I prefer the tagging method. That way it's a conscious decision to post a microblog post in a community.