GGUF is at least better than bnb. From what I know, bnb does not yet find a way to quantize MoE with enough accuracy, and maintain the dequant-MoE kernels. In the age of Qwen 3.0, people tried to make some bnb '4-bit' quants of MoE models, but actually the MoE part is not quantized. It's a pity that even Unsloth gave up low-VRAM finetuning with MoE (although they're making their GGUFs for inference), and the world of local training looks stagnated for months.

GGUF is maintained by all the llama.cpp developers. There are many quantization formats and algorithms under this container format, some are optimized for MoE (such as APEX quant), some for CPU and some for GPU, some work surprisingly well below 4-bit (and even near 1-bit). It also supports recent architectures like linear attentions and mHC.