If I understand you correctly, you’d be looking for something like below?
I don’t think there is a pretty way to do that, what does seem to work is add a calculated column to the table with your Projects ranking them and add that [Sort] field to the Column section of the matrix first followed by [Projects] and then expand a level down in hierarchy (because this doesn’t work with a measure).
Downside is that unlike a column you can’t hide the [Sort] row by resizing it so it will remain visible.
Perhaps instead you could add a rank as prefix to your Project ID??
But maybe someone else has a better idea.