It's end of April 2021 and I was able to install the beta driver for Big Sur for my MBP 2015 using LandingZone dock. Had to disable SIP and all that jazz. However, I noticed that com.asix.dext.usbdevice is on 100% CPU usage, and on my 1Gbit internet connections I am getting max 100kbps (via speedtest.net). As soon as I disconnect the LAN and switch to WiFi, I am getting ~450kbps. So something is not well with this driver.