See: Hyper-V: Autostart Dekstop GUI not working - #4 by rmscode
Fresh start of the DietPi Hyper-V image according to the guide.
Install the Xfce (include X11, audio dependencies automatically)
calling startx generates “Cannot run in framebuffer mode…”
If set for autostart, must use SSH to issue commands.
Off to a poor start testing this option.
Did Ubuntu Server with Xfce on Hyper-V without issue.