Blender 2.8: Move (g) a face like in the direction, extrude would do, when object is "sheared"? "Extrude" always extend a face in the direction of the face normal.
Having a "sheared" object (see below):
How can I acchieve the same behaviour when moving a face with "g"?
You can do it switching the transformation orientation to 'normal', then grab G and use Z to indicate the Z axis which is by convention the normal direction.