ok let’s ask the other way around. Do you need the desktop directly on your RPi just for the Initial setup or do you need it later on as well?
Because you can simply install RealVNC from DietPi software catalog. no need for any other desktop software. This all can be setup completely headless.
Still my question, how do you connect. Do you use just the IP on the RealVNC client or do you add a :1 at the end?
https://dietpi.com/forum/t/resolved-removing-diversion-of-boot-overlays-readme-err/74/1