How to open gui applications like firefox in the Qt Wayland compositor which I created

I created an example Qt Wayland compositor and the QML code goes like this:

import QtQuick 2.15
import QtQuick.Window 2.15
import QtQuick.Controls 2.0
import QtWayland.Compositor 1.0

WaylandCompositor{
    id:comp
    WaylandOutput{
        compositor:comp
        sizeFollowsWindow:true
        window:Window{
            visible:true
            width:700
            height:700
            Repeater{
                model:shellSurfaces
                ShellSurfaceItem{
                    shellSurface:modelData
                    onSurfaceDestroyed:shellSurfaces.remove(index)
                }
            }
        }
    }
    ListModel{id:shellSurfaces}
    WlShell{
        onWlShellSurfaceCreated:{
            shellSurfaces.append({shellSurface:shellSurface});
        }
    }
}

I know I can open a wiggly window using --platform wayland after the command. How can I open other software windows in the Wayland compositor(for example Firefox)?

(I don't know the basics of display servers and Wayland compositors. I think the compositor that I've created is just like a window manager and the apps that I open in it should just open in the compositor as it opens in a window manager).

When your compositor loads, it creates a socket on your computer. On my machine, it is located in /run/user/1000. It should be named something like 0-wayland.

In order to launch an app you need to pass the wayland display to it via a environment variable.

Example:

Launch firefox : WAYLAND_DISPLAY=wayland-0 XDG_RUNTIME_DIR=/run/user/1000 XDG_SESSION_TYPE="wayland" firefox

Launch kcalc(KDE's calculator): WAYLAND_DISPLAY=wayland-0 XDG_RUNTIME_DIR=/run/user/1000 XDG_SESSION_TYPE="wayland" kcalc

I think you get the idea.