There are some models like:
https://huggingface.co/Terfo/nutmegmix-AbyssOrangeMix/tree/main

https://huggingface.co/google/gemma-3n-E4B-it-litert-lm/tree/main

and other single file diffusion models which do not have a config file. Currently the system throws an error if the model being loaded doesn't have a config.json.