How to make .desktop file to open with its own icon in sidebar

I have created a .desktkop file to open GitHub using brave browser

#!/usr/bin/env xdg-open
[Desktop Entry]
Name=GitHub
GenericName=GitHub
Comment=Github desktop app
Exec=/opt/brave.com/brave/brave-browser --profile-directory="Default" --app=https://github.com/
Icon=/home/parag/.icons/github-desktop.svg
Terminal=false
Type=Application
StartupNotify=true
MimeType=text/plain;
Categories=Network;Application;
Keywords=Github;gitapp;
X-Ubuntu-Gettext-Domain=Github

But the problem is that it comes as an instance of the browser with the browser icon in the sidebar.

I want it to show its own icon in the sidebar instead of the browser icon.

Is there any way to do it??

thanks in advance :))

Edit 1

I tryed Alt+F2 and typed lg and go to the windows section and here is the output

here WhatsApp opens as desired (with its own icon in the sidebar) but Github doesn't.

The only difference here is that app field for WhatsApp shows the desktop filename while for Github it shows the browser's desktop file name.

So does this mean that a desktop file opening a website will have its separate icon if only if the website is a web app?