Do you mean something such as what I would call “named ordered collections”, where each of them has its own special sort order? I was writing about how I imagine such a feature and its implementation several times, but I totally failed to explain it in a way that made sense for others. See e.g. the thread below:
Sorting itself is now implemented, but I had no time yet to test it. But I still think an additional collection functionality that does not follow darktables parametric approach but is only defined by images selected by the user (but where additionally the parametric sorting can be applied) would be beneficial.