Thank you. I installed Real VNC Viewer on my Windows Desktop and Android Phone.
Next did following on RPi:
STEP-1: I had Raspbian Lite image, so I SSH to RPi and enabled VNC Server as follows:
pi@raspberrypi:~ $ sudo raspi-config
STEP-2: Fired up VNC Viewer on Windows PC, got this
STEP-3: Added GUI to RaspberryPi OS LITE by following commands
sudo apt update
sudo apt install raspberrypi-ui-mods
sudo apt install rpi-chromium-mods
sudo reboot
STEP-4: Again fired up VNC Viewer on Windows Dsektop, and this time it connected to the RPi’s Desktop
STEP-5: The VNC server by default connects to VNC viewer on same router/LAN. To connect VNC Viewer on a Computer/Phone from internet, did following:
5 (a) Created a cloud account at real VNC using email
5 (b) Connected to RPi VNC Server from Widows Desktop on same router/LAN and changed default setting as shown in screenshot below
Effect of adding GUI and activating VNC Server on performance of RPi
CONCLUSION: I dont need VNC / GUI. I need SSH. Zerotier is better for me as suggested by @foxhunter