The example being talked about is:
https://doc.qt.io/qt-6/qml-qtquick3d-assetutils-runtimeloader.html

Step to reproduce:
1. Build the example and deploy
2. Either run by passing a .glb file to it as argument or import one from UI. .glb files for test can be found in my comment.

Result:
Status: Unsupported: Unknown error

The reason is that somehow the RuntimeLoader source is erased. I've put a

            onSourceChanged: {
                console.log("The source file is " + source)
            }

inside RuntimeLoader, and the log goes like

qml: The source file is file:///usr/bin/mercedes.glb
qml: The source file is

"mercedes.glb" is the .glb file for test I put in /usr/bin, and the first entry is expected. Then the source is cleared for some resaon. And the error "Status: Unsupported: Unknown error" shown on screen.

BTW, the problem is only seen on QNX for now. The example runs well on desktop. So maybe a file system issue or some sort of security policy on QNX?

Update: packing .glb into resource does not work either. The source of RuntimLoader still becomes empty automatically somehow. And still the same "Status: Unsupported: Unknown error" error.