I think the navigation widget is different than a lot of the other widgets because navigation is sort of standalone anyway (only deals with the map, not any of your layers etc). I wouldn't expect to see hardly anyone pulling apart the widgets and converting them to standalone.
I wouldn't recommend that you even try. There is a lot of overhead involved that keeping the widget interaction going that completely falls apart once you start to use just parts of a widget . (Unless you're a programmer, then go for it!) Otherwise, if there are certain pieces of functionality you need, there are lots of examples in the API reference.
Personally I'm not a fan of the widget approach because I see people put a lot of extra tools in their map because they're easy to add, not because they really need them. I seem to be in the minority, though.