Thanks for pointing out those models. I see from a quick Huggingface search that the bge model is available in GGML format. You can trivially add new GGML format models to the code by simply adding the direct download link to this line:

https://github.com/Dicklesworthstone/llama_embeddings_fastap...

So to add the base bge model, you could just add this URL to the list:

https://huggingface.co/maikaarda/bge-base-en-ggml/resolve/ma...

I will add that as an additional default.