Fuji shooters know that there are virtually no real third party alternatives to Fuji lenses for their cameras. Sure, there are a few manual focus ones and even cine lenses out there, but nothing autofocus that really competes with Fuji’s own lenses. This is because Fujifilm has typically always declined to share the X mount spec with 3rd party lens manufacturers.
Of course, Fujifilm’s Toshihisa Iida said back in April that they were going to start sharing them with 3rd parties soon, although we’ve seen no new lenses yet. A response by Sigma to a customer enquiry, however, suggests that might be changing and that X mount Sigma lenses could be coming in 2021.