FPGAs have really low density so that would be ridiculously inefficient, probably requiring ~100 FPGAs to load the model. You'd be better off with Groq.

Not sure what you're on but I think what you said is incorrect. You can use hi-density HBM-enabled FPGA with (LP)DDR5 with sufficient number of logic elements to implement the inference. Reason why we don't see it in action is most likely in the fact that such FPGAs are insanely expensive and not so available off-the-shelf as the GPUs are.