Yea, you could pass it in directly to the storage context
`StorageContext.from_defaults(docstore=docstore, index_store=index_store, ...)
index = VectorStoreIndex([], storage_context=storage_context)
```
Although if you are using Google cloud buckets, I think there is support for fsspec integration
https://gpt-index.readthedocs.io/en/stable/core_modules/data_modules/storage/save_load.html#using-a-remote-backend