Work around for VoiceOver Context menu (VO+Shift+M) not working on the Dock in Mac OS Big Sur 11.1 (20C69)
Simply 3 steps:
In VoiceOver Utility/Navigation, choose Mouse to follow VoiceOver cursor,
Make sure VoiceOver Trackpad Commander is turned off by VO+2 finger rotate counter clockwise, and
Control+Click when in the Dock via VO+D to bring up the Context Menu.