which then causes a lookup of Navigation.qml (and yeah, I did still have to give it an alias in the .qrc file, for some reason...)
Not sure why I had to do this from my reading of the documentation, but it's at least a workable solution.
Seems like QML only resolves components only with .qml extension.
Your solution wokrs because import "./components" as Components imports the whole folder 'navigation'. Then you use the component Components.Navigation, which then is loaded by the engine as Navigation.qml.