Following the lead of Canon, who introduced a software for Windows (June 2020) and for macOS (July 2020) that turns its cameras into webcams, Fujifilm has introduced a similar software named "FUJIFILM X Webcam".
Beyond simply improving the image quality over conventional webcams, thanks to significant increase in sensor size as well as, in select models, to advantages of Fujifilm's X-Trans sensors (that delivers image quality comparable to full-frame at APS-C size; read more here), Fujifilm also throws in support for Film Simulation modes when using the cameras as webcams.
Initially, the more recent higher-end models received support: GFX100, GFX 50S, GFX 50R, X-H1, X-Pro2, X-Pro3, X-T2, X-T3, X-T4.
Three weeks after initial release of X Webcam, Fujifilm also released firmware updates for the X-A7 and X-T200 that added compatibility with the X Webcam software.
X Webcam can be downloaded here.