Converting a headless jeson nano to a screen+keybaoard one

I managed to have my jetson nano working in a headless way (teraterm+ssh).
I think it would be more comfortable to work with a screen, a keybeard and a mouse.
Do I have to flash another SD card, or is it easy to adapt the existing one?
Is it possible to have both the headless mode and the “desktop” mode on the same SD(my RPi can work either through ssh, sometimes without screens, or with a desktop)

You could just plug this sdcard out and to another device.

Is it possible to have both the headless mode and the “desktop” mode on the same SD(my RPi can work either through ssh, sometimes without screens, or with a desktop)

This depends on how was your setup to make the device headless. If you don’t remove the kernel driver, then the HDMI and USB should always work.

Well, thanks for encouragement.
Maybe it will be easy to restore a desktop (I used the script “unminimize”, which restored desktop packages) Ssh and teraterm ( a putty substitute) kept working after rebooting.
Maybe I can be very happy with remote connections a give my HDMI screen to RPI : jetson <- (ssh/scp or screen) ->RPi<->HDMI+mouse+keyboard