import json
with tempfile.TemporaryDirectory() as tmp_dir:
     model.save_pretrained(tmp_dir, max_shard_size="200MB")
     with open(os.path.join(tmp_dir, "pytorch_model.bin.index.json"), "r") as f:
         index = json.load(f)
print(index.keys())
dict_keys(['metadata', 'weight_map'])

The metadata just consists of the total size of the model for now. We plan to add other information in the future:

index["metadata"]
{'total_size': 433245184}