Check a blog about this at https://www.coolsmartphone.com/2018/08/08/huawei-desktop-mode-in-depth/
Useful USB hub can be the USB-C to HDMI and USB-2 hub: https://www.gearbest.com/usb-gadgets/pp_009950320216.html?wid=1433363¤cy=GBP&vip=4264395
Or do a search on Google for other USB-C HDMI hub. The prices can vary very much: https://www.gearbest.com/usb%20c%20hub%20hdmi-_gear/