If GPT_Index uses LangChain, I recently added support for Azure OpenAI completions there. Azure OpenAI (
https://aka.ms/azure-openai) has same models as OpenAI but in a separate stack with cloud provider features like privacy & SLA. If you're looking for OSS that's a different story, but check it out if it meets your use case. Happy to get on a call - DM me if interested.