@LeLev Thank you very much for your answer. It helped me to understand my issue a little more. So I tried your code, and it works, meaning that the ListView isn't eating the Space key.
However my interface is a little more complex than this one, it contains other objects like SwipeView, and yes, my items contain components like buttons which may take the focus. However I already tried to deactivate them and even thus the issue remained.
I played a while around the code you posted. I noticed that the following code no longer receives any key:
Rectangle
{
    anchors.fill: parent
    color: "transparent"
    visible: true
    SwipeView
    {
        anchors.fill: parent
        activeFocusOnTab: false
        Page
        {
            background: null
            ListView
            {
                id: view
                anchors.fill: parent
                spacing: 2
                focus: true
                model: ListModel
                {
                    ListElement
                    {
                        name:  "el1"
                    }
                    ListElement
                    {
                        name:  "el2"
                    }
                    ListElement
                    {
                        name:  "el3"
                    }
                }
                delegate: Button
                {
                    focus: false
                    focusPolicy: Qt.NoFocus
                    onFocusChanged: {if (focus) focus = false;}
                    width: parent.width
                    height: 50
                    text: index === view.currentIndex ? "currentIndex" :  modelData
                    onClicked:
                    {
                        view.currentIndex = index
                    }
                }
                Keys.onPressed:
                {
                    console.warn("key clicked");
                    if (event.key === Qt.Key_Space)
                    {
                        console.log("space clicked");
                        console.log(view.model.get(view.currentIndex).name); // view.model.get(ind).name = "new value"
                        event.accepted = true;
                    }
                }
            }
        }
    }
}
So I assume that some components operate like filters and may stop internally the keyboard signals, or at least a part of them, without let the choice to the developer to bypass this behavior (or at least I don't know how to do). To be honest I'm a little puzzled, because I worked for15 years with the Windows API before changing for Qt, and receiving a keyboard notification was never an issue, even when the parent component already received it before (in fact it was the contrary: the message could be blocked in the parent, but by default it was passing).
So now the question is: in the above code, how can I receive the keyboard signals, and in particular the Space key, in my ListView despite of the parent SwipeView? Or which solution is normally used in a such situation, e.g is there a way to globally listen the keyboard and intercept keys in the Windows level, BEFORE any component receives them?