You can use conv layers to have single levels (using coeffs eg from pywavelets and setting requires_grad to False.
Also check out

  
      
      GitHub
  
  
    

edouardoyallon/pyscatwave 228

pyscatwave - Fast Scattering Transform with CuPy/PyTorch


  
  
    
    
  
  


that seems to be the most waveletty neural network thing I have recently seen.
I think I saw Edouard around here, but I forgot his username.
Best regards
Thomas