How to sneak namespacing into hashtags in the style of RDF Turtle / CURIEs. Perhaps · ("middle dot", \u00B7) will work?
Does #skos·Concept work?
relevant mastodon source code: https://github.com/mastodon/mastodon/blob/ed570050c62115cfbcca8cfcd0de891b729f3e5c/app/models/tag.rb#L29