can I cmd+drag a shape layer to make another layer like i can with a group?

If you want to keep everything vector, there's two possible approaches.

The simplest way would be to put the shape layer you want to mask above the shape layer you want to use as a mask and create a clipping mask (Alt or Option click the divider line between the two layers).

Another way would be to select the path you want to use as the mask with the Path Selection tool, and copy it. Then target the shape layer you want to mask in the Layers panel, and paste the mask you copied. You will now have two paths on the same layer. With the pasted path still selected, click on the Pen tool. In the Options bar at the top of the screen, select Intersect Shape Areas.