Hi Paolo & Bienvenuto a te ;-)
The upgrade from one release to another (7 to 8) is not available yet,
Trisquel 8 is still Alpha, nevertheless you can install Lxde (even Lxqt),
Xfce,Cinnamon with your Synaptic Package Manager.
https://trisquel.info/fr/forum/lxqt-available-trisquel-8-flidas-alpha-flidas
RazorQt is the second desktop environment by default in the Mate version (by
selecting at the login with the Trisquel logo) you will have to add
razor-panel to make it more functional.
Cheers
;-)
I had no success with the Netinstall images either..
