Blocks like gravel and sand can be gotten in their block form by making them fall onto something they cannot sit on (bottom slab, torch, trapdoor or even wooden button which is easy to get early on).
While this doesn't look like it breaks the progression it's a way to bypass the compacting bin for getting gravel and sand blocks.
If possible it would be nice if they dropped the same contents you would get when you normally break them, would feel more consistent and logical.

Related to codetaylor/dropt-1.12/issues/75