Thanks for creating https://doc.qt.io/qt-6/qml-singleton.html this was really something missing .

I noticed though that the https://doc.qt.io/qt-6/qml-singleton.html#defining-singletons-in-qml says that we need to write

pragma singleton

I think it should be:

pragma Singleton

Not writing singleton with a capital S leads to a compile error error:
Error compiling qml file: C:/work/Qt/SingletonForFonts/Globals.qml:1:1: error: Unknown pragma 'singleton'