Is this not just grouped convolution? If it’s anything like this paper: https://arxiv.org/pdf/1610.02357.pdf 151
then I think it is.
Example for mobile-net:
conv = nn.Sequential(
               nn.Conv2d(1, N, kernel=(3, 3), stride=(2, 2)),
               nn.Conv2d(N, N, kernel=(3, 3), stride=(2, 2), groups=N),
               nn.Conv2d(N, 1, kernel=(1, 1), stride=(1, 1))
       )