Hashtags in a federated setting are an interesting technical and UX challenge.
In the push direction, I am not too worried: at least one account follows me from most large instances.
In the pull direction though I lost ~all visibility moving to a personal instance.
I don't want a firehose relay (of which anyway there's no reliable ones), but maybe there should be such a thing as a #hashtag relay where you get posts with hashtags followed by people on the local instance?