upgrade-raspbian-lite-to-desktop
https://raspberrytips.com/upgrade-raspbian-lite-to-desktop/

When you install Raspberry Pi OS with Desktop, you get the PIXEL Desktop environment.

   Use Tasksel:
sudo apt update
sudo apt upgrade
sudo apt dist-upgrade
sudo reboot
sudo tasksel
   little resources: LXDE, XFCE (etwas flexibleres outfit, braucht dann aber mehr memory)
sudo raspi-config: 
   auto-login
   options, on how you want to start your system: Desktop
       I guess you’ll have to change for “Desktop” or “Desktop Autologin” 
reboot now


sudo update-alternatives --config x-session-manager (wechseln verschiedener desktops)
sudo apt install synaptic
evtl. sudo apt install synaptic, sudo apt install chromium-browser