I guess you have a FFT library. You probably should write an efficient Walsh Hadamard transform library to allow people to better experiment with fast transform neural networks:

https://community.konduit.ai/t/fast-transform-neural-net-visual-example/497

Since the Walsh Hadamard transform is just the additive part of the FFT maybe you just need to take the multiplies out of your FFT code!!! Then maybe you could provide the switch slope at zero parametric functions. That is all you need.

As part of a ML framework, maybe do auto differentiation.