If you still need a solution ContentPeerPicker works fine:

ContentPeerPicker {
    anchors { fill: parent }
    visible: parent.visible
    showTitle: false
    contentType: ContentType.All
    handler: ContentHandler.Source

    onPeerSelected: {
        picker.activeTransfer = peer.request()
        picker.activeTransfer.stateChanged.connect(function() {
            if (picker.activeTransfer.state === ContentTransfer.Charged) {
                console.log(picker.activeTransfer.items[0].url)
                picker.activeTransfer = null
            }
        })
    }
}

(example provided under the CC0 license)
You can show it in a dialog when user clicks a button.

Here you have a complete example of importing a file using ContentHub in QML: https://api-docs.ubports.com/sdk/apps/qml/Ubuntu.Content/ContentHub.html#detailed-description

Basically you have to create a ContentPeer:

ContentPeer {
    id: picSourceSingle
    contentType: ContentType.Pictures
    handler: ContentHandler.Source
    selectionType: ContentTransfer.Single
}

Have a place to store the transfer:

property var activeTransfer

Then in the click handler start the request:

onClicked: {
    activeTransfer = picSourceSingle.request()
}

And handle the transfer result:

Connections {
    target: root.activeTransfer
    onStateChanged: {
        if (root.activeTransfer.state === ContentTransfer.Charged) {
            setImg.source = root.activeTransfer.items[0].url;
        }
    }
}

I adapted it a bit to your code, hopefully you are able to integrate it completely.

Thanks for your time

Here is my 3 fies.

clickable.json:

{
  "clickable_minimum_required": "6.22.0",
  "builder": "pure-qml-cmake",
  "kill": "qmlscene"
}

I found this here (https://docs.ubports.com/en/latest/appdev/platform/apparmor.html#networking)

and i set into (.apparmor)

.apparmor:

{
    "policy_groups": ["camera", "document_files", "picture_files"],
    "policy_version": 16.04
}

my Main.qml code:

import QtQuick 2.7
import Ubuntu.Components 1.3
//import QtQuick.Controls 2.2
import QtQuick.Layouts 1.3
import Qt.labs.settings 1.0
import QtQuick.Window 2.12
import QtQuick.Controls 2.5
import QtQuick.Dialogs 1.2
import Qt.labs.folderlistmodel 2.2

MainView {
    id: root
    objectName: 'mainView'
    applicationName: 'ufile.ufile'
    automaticOrientation: true

    width: units.gu(45)
    height: units.gu(75)

    Column{
        anchors.verticalCenter: parent.verticalCenter
        anchors.horizontalCenter: parent.horizontalCenter

        Row{
            Button {
                id: btn
                text: "Open"
                onClicked: fileDialog.open();
            }
        }

        Image {
            id: setImg
            width: 300
            height: 300
            source: "/home/fredy/Pictures/Screenshot from 2021-10-22 11-29-16.png"
        }

        FileDialog {
            id: fileDialog
            title: "Please choose a file"
            folder: shortcuts.home
            onAccepted: {
                var setFiles = fileDialog.fileUrls
                console.log("You chose: " + fileDialog.fileUrls)
                setImg.source = setFiles[0]
                //Qt.quit()
            }
            onRejected: {
                console.log("Canceled")
                //Qt.quit()
            }
        }
    }
}

Best Regards
007fred50

The linked documentation also links to the source code of an app that uses it to select images: https://gitlab.com/cibersheep/webapp-creator/blob/master/webapp-creator/app/ImportPage.qml#L38

Not sure about the last error, can you post your clickable.json and .apparmor file?