Thanks for the feedback. I understood the docs, but I wanted to use the cross product in 2D.
Finally, I ended up doing this, if someone is having the same issue.
 # pad the last dim to have 3D vector 
s_pad = F.pad(s, (0, 1))
# compute the cross product 
A = torch.cross(s_pad[:, index_list], s_pad[:, index_list_plus], dim=2)
# use the last dim which is the same as if the cross product would be done in 2D
A = A[..., 2]