This guide uses Deskreen on Pop! OS 20.04

Deskreen can share any display as long as it is detected via xrandr, but to be able to have a display show up exlusively on a secondary device, there needs to be an unused display output. Most GPUs and laptops have additional display-out ports (HDMI/DisplayPort/DVI) that can be used. But in my case, I use my TV as a primary display, while casting my laptop's screen to my phone, as my laptop's display doesn't work anymore.

The output will be something like this.

Monitors: 2
 0: +*HDMI-A-0 1920/575x1080/323+0+0  HDMI-A-0
 1: +eDP 1366/344x768/193+1920+0  eDP

As you can see, I have total 2 display outputs, HDMI-A-0 (HDMI Port) and eDP (laptop's primary display, which is currently unused).

# REPLACE THESE VARIABLES WITH YOUR OWN VALUES:
virtual_output_name=eDP # Unused output that you want to use for Deskreen
desired_resolution_width=1366 # Put the max for your display (eg. 1920)
desired_resolution_height=768 # Put the max for your display (eg. 1080)
relative_position=right-of # Options: right-of, left-of , above, below
relative_to_output_name=HDMI-A-0 # My current display that I used as a reference

xrandr --output $virtual_output_name --mode "$desired_resolution_width"x$desired_resolution_height --$relative_position $relative_to_output_name 

echo -e "\nEXECUTING: \n"
echo -e xrandr --output "$virtual_output_name"
echo -e --mode "$desired_resolution_width"x"$desired_resolution_height"
echo -e --"$relative_position" "$relative_to_output_name" "\n"; xrandr

# processed command will look like:
# xrandr --output eDP --mode 1366x768 --right-of HDMI-A-0

EXECUTING: xrandr --output eDP --mode 1920x1080 --right-of HDMI-A-0 

Screen 0: minimum 320 x 200, current 3286 x 1080, maximum 16384 x 16384
eDP connected 1366x768+1920+0 (normal left inverted right x axis y axis) 344mm x 193mm
  1366x768      60.00*+  47.99  
  1280x720      60.00  
  1024x768      60.00  
  800x600       60.00  
  640x480       60.00  
  1920x1080     60.00  
HDMI-A-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 575mm x 323mm
  1920x1080     60.00*+  60.00    50.00    59.94    24.00    23.98  
  1680x1050     59.88  
  1280x1024     60.02  
  1440x900      60.00  
  1280x960      60.00  
  1360x768      60.02  
  1280x800      59.91  
  1280x720      60.00    50.00    59.94  
  1024x768      60.00  
  800x600       60.32    56.25  
  720x576       50.00  
  720x480       60.00    59.94  
  640x480       60.00    59.94  
  720x400       70.08 

Now that all the technical jargon is over, we can finally head to the easy part!

Go ahead and download Deskreen client as a deb or AppImage file (depending on your system), from their official website.

I am using my Android Phone as a secondary device here, but feel free to use any reasonable device with a recent enough browser (Firefox, Chrome, Safari)

After opening Deskreen,

• If you are using a mobile phone, scan the QR code shown there, which will open a link in the browser
• Or, you can simply enter the URL shown below the QR Code in the browser of another device.

But remember, the link changes when the remote device is disconnected, and you will have to allow the device everytime.



• Deskreen will then ask you if you want to allow the device while trying to connect.



• From there, choose between sharing an entire screen, or just a specific window.



• I am going to share the virtual screen that I just created above!



• Confirm the choices, or change something if you need to.



• And, Voila! I have my phone as a secondary display for my laptop, which works wirelessly! :D