I am actually getting interested in QAT these days, especially for LSQ+ type, but it doesn't seem like people have done that enough in open-source world at least, for 2-bit / 3-bit OPD with LSQ+ basically.

the industry has largely moved away from QAT because the hardware required for running a quantized model are an order of magnitude less than training/QATing the fp model.

That's why things like Autoround, GPTQ, AWQ have been so popular, you don't even need enough hardware to run the original model on gpu, just cpu is enough due to the data efficiency